2s,3r)-n-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl-benzyofuran-2-carboxamide, novel salt forms, and methods of use thereof

ABSTRACT

The present invention relates to (2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide, novel salt forms thereof, methods for its preparation, novel intermediates, and methods for treating a wide variety of conditions and disorders, including those associated with dysfunction of the central and autonomic nervous systems.

CROSS RELATION TO PRIOR APPLICATIONS

The present invention claims benefit to U.S. Provisional ApplicationNos. 60/971,654, filed Sep. 12, 2007, 60/953,610, filed Aug. 2, 2007,60/953,613, filed Aug. 2, 2007, and 60/953,614 filed Aug. 2, 2007, eachof which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,novel salt forms thereof, methods for its preparation, novelintermediates, and methods for treating a wide variety of conditions anddisorders, including those associated with dysfunction of the centraland autonomic nervous systems.

BACKGROUND OF THE INVENTION

The neuronal nicotinic receptors (NNRs) characteristic of the centralnervous system (CNS) have been shown to occur in several subtypes, themost common of which are the α4β2 and α7 subtypes. See, for example,Schmitt, Current Med. Chem. 7: 749 (2000), herein incorporated byreference. Ligands that interact with the α7 NNR subtype have beenproposed to be useful in the treatment of a variety of conditions anddisorders. See Mazurov et al., Curr. Med. Chem. 13: 1567-1584 (2006) andreferences therein herein incorporated by reference with regard tobackground understanding of the α7 neuronal nicotinic receptor subtype.Prominent among those conditions and disorders are cognitive impairment,schizophrenia, inflammation, angiogenesis, neuropathic pain, andfibromyalgia.

There are a decreased number of hippocampal NNRs in postmortem braintissue of schizophrenic patients. Also, there is improved psychologicaleffect in smoking versus non-smoking schizophrenic patients. Nicotineimproves sensory gating deficits in animals and schizophrenics. Blockadeof the α7 NNR subtype induces a gating deficit similar to that seen inschizophrenia. See, for example, Leonard et al., Schizophrenia Bulletin22(3): 431 (1996), herein incorporated by reference. Biochemical,molecular, and genetic studies of sensory processing in patients withthe P50 auditory-evoked potential gating deficit suggest that the α7 NNRsubtype may function in an inhibitory neuronal pathway. See, forexample, Freedman et al., Biological Psychiatry 38(1): 22 (1995),incorporated by reference.

More recently, α7 NNRs have been proposed to be mediators ofangiogenesis, as described by Heeschen et al., J. Clin. Invest. 100: 527(2002), incorporated by reference. In these studies, inhibition of theα7 subtype was shown to decrease inflammatory angiogenesis. Also, α7NNRs have been proposed as targets for controlling neurogenesis andtumor growth (Utsugisawa et al., Molecular Brain Research 106(1-2): 88(2002) and U.S. Patent Application 2002/0016371, each incorporated byreference). Finally, the role of the α7 subtype in cognition (Levin andRezvani, Current Drug Targets: CNS and Neurological Disorders 1(4): 423(2002)), neuroprotection (O'Neill et al., Current Drug Targets: CNS andNeurological Disorders 1(4): 399 (2002) and Jeyarasasingam et al.,Neuroscience 109(2): 275 (2002)), and neuropathic pain (Xiao et al.,Proc. Nat. Acad. Sci. (US) 99(12): 8360 (2002)) has recently beenrecognized, each citation herein incorporated by reference.

Various compounds have been reported to interact with α7 NNRs and havebeen proposed as therapies on that basis. See, for instance, PCT WO99/62505, PCT WO 99/03859, PCT WO 97/30998, PCT WO 01/36417, PCT WO02/15662, PCT WO 02/16355, PCT WO 02/16356, PCT WO 02/16357, PCT WO02/16358, PCT WO 02/17358, Stevens et al., Psychopharm. 136: 320 (1998),Dolle et al., J. Labelled Comp. Radiopharm. 44: 785 (2001) and Macor etal., Bioorg. Med. Chem. Lett. 11: 319 (2001) and references therein,such references incorporated by reference with regard to backgroundteaching of α7 NNRs and proposed therapies. Among these compounds, acommon structural theme is that of the substituted tertiary bicyclicamine (e.g., quinuclidine). Similar substituted quinuclidine compoundshave also been reported to bind at muscarinic receptors. See, forinstance, U.S. Pat. No. 5,712,270 to Sabb and PCTs, WO 02/00652 and WO02/051841, each of which is incorporated by reference with regard tosuch compounds.

A limitation of some nicotinic compounds is that they are associatedwith various undesirable side effects, for example, by stimulatingmuscle and ganglionic receptors. There continues to be a need forcompounds, compositions, and methods for preventing or treating variousconditions or disorders, such as CNS disorders, including alleviatingthe symptoms of these disorders, where the compounds exhibit nicotinicpharmacology with a beneficial effect, namely upon the functioning ofthe CNS, but without significant associated side effects. There is aneed for compounds, compositions, and methods that affect CNS functionwithout significantly affecting those nicotinic receptor subtypes whichhave the potential to induce undesirable side effects, such asappreciable activity at cardiovascular and skeletal muscle sites. Thepresent invention provides such compounds, compositions, and methods.

SUMMARY OF THE INVENTION

One aspect of the present invention is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof. Another aspect is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,in substantially pure form, or a pharmaceutically acceptable saltthereof. A further aspect is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,substantially free of (2S,3S), (2R,3S), or (2R,3R) isomers, or apharmaceutically acceptable salt thereof.

Further, another aspect is stereoisomerically enriched(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,or a pharmaceutically acceptable salt thereof. In one embodiment, theenantiomeric and/or diastereomeric excess is 90% or greater. In oneembodiment, the enantiomeric and/or diastereomeric excess is 95% orgreater. In one embodiment, the enantiomeric and/or diastereomericexcess is 98% or greater. In one embodiment, the enantiomeric and/ordiastereomeric excess is 99% or greater. In one embodiment, theenantiomeric and/or diastereomeric excess is 99.5% or greater.

Another aspect of the present invention is an acid salt of(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,wherein the acid is selected from hydrochloric acid, sulfuric acid,phosphoric acid, maleic acid, p-toluenesulfonic acid, galactaric (mucic)acid, D-mandelic acid, D-tartaric acid, methanesulfonic acid, R- andS-10-camphorsulfonic acids, ketoglutaric acid, or hippuric acid. In oneembodiment, the stoichiometry of(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideto the acid is 2:1, 1:1, or 1:2. In one embodiment, the stoichiometry is1:1. One embodiment of the present invention is(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehydrochloride or a hydrate or solvate thereof, including partialhydrates or solvates. A further embodiment is(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride or a hydrate or solvate thereof, including partialhydrates or solvates.

The present invention also provides a scalable syntheses of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideand novel intermediates.

The scope of the present invention includes all combinations of aspects,embodiments, and preferences herein described.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A1-1A4 illustrate responses of rat α7 receptors expressed inmammalian GH4C1 cells to(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide;the racemate, namely a mixture of (2S,3R), (2R,3S), (2R,3R), and(2S,3S); the individual stereoisomers; and acetylcholine (ACh).

FIG. 1B illustrates a comparison of the functional responses of rat α7receptors expressed in mammalian GH4C1 cells to(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide;the racemate, namely a mixture of (2S,3R), (2R,3S), (2R,3R), and(2S,3S); and the individual stereoisomers within the effective plasmaconcentration range.

FIG. 2A illustrates responses of human α7 receptors expressed in Xenopusoocytes to(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide.

FIG. 2B illustrates control responses of human α7 receptors followingthe application of the compound at the indicated concentrations. Datawere normalized to the net charge of control 300 μM ACh responsesobtained 5 min before the experimental agonist-evoked responses. Eachpoint represents the average±SEM of the normalized responses of at least4 oocytes.

FIG. 3 illustrates an assessment of cognitive effects in an objectrecognition (OR) paradigm, demonstrating that(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehas positive effects at 0.3 and 1 mg/kg administered i.p., *p<0.5.

FIG. 4 illustrates an assessment of cognitive effects in an OR paradigm,demonstrating that(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide administered p.o. has positive effects over awide dose range (0.3-10 mg/kg), *p<0.5.

FIG. 5 illustrates effects of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideadministered i.p. in preventing cognitive deficits induced by MK-801,also known as dizocilpine, a commercially available non-competitiveantagonist of the NMDA receptor, in the OR task.

FIG. 6 illustrates that an average time spent on object A versus objectB, in OR task, by the vehicle-treated group at 30 min, 6 h, or 24 hafter the final sub-acute administration (p.o.) trial was notsignificantly different (p=0.17, p=0.35 and p=0.12, respectively).Alternatively, at 30 min, 2 h, 6 h, and 18 h after the final sub-acuteadministration of 0.3 mg/kg(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,subjects spend significantly (P<0.05) more time investigating object B(novel) than object A (familiar). Moreover, at 2 h (75%) and 6 h (71%)the recognition index was significantly improved in animals treated with0.3 mg/kg(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidecompared to the recognition index (54%) of the vehicle-treated group at30 minutes after final administration.

FIG. 7 illustrates an assessment of cognitive effects in a radial armmaze (RAM) paradigm.(2S,3R)—N-(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(0.1, 0.3 and 1.0 mg/kg) was administered p.o. 30 minutes prior to thedaily session. An improvement in performance on the task was evident inthe group treated with 0.3 mg/kg(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideduring the second week of administration.

FIG. 8 illustrates a study of antipsychotic effects, measured ashyperactivity behavior induced by dopamine over-stimulation, showingthat(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(0.3 and 1.0 mg/kg; s.c.) attenuates locomotor hyperactivity induced byapomorphine (1.0 mg/kg) following subcutaneous administration in rats.

FIG. 9 illustrates an antipsychotic assessment, prepulse inhibition,indicating that apomorphine-induced deficits are reversed withpretreatment of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidefollowing subcutaneous administration.

FIG. 10A illustrates the results of the x-ray crystallographic analysisof(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride, establishing the absolute stereochemistry of thismaterial. The depicted compound is the partially hydrated hydrochloridesalt, as shown with the fully ordered chloride anion and partiallyoccupied molecule of water in the asymmetric unit.

FIG. 10B illustrates the results of the x-ray crystallographic analysisof(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride, establishing the absolute stereochemistry of thismaterial, depicted with a numbering scheme for reference. The view islooking down the crystallographic b-axis of the unit cell. Theinter-molecular hydrogen bonds are shown as dashed lines.

FIG. 11A illustrates the results of the x-ray crystallographic analysisof(2R,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidep-chlorobenzoate, establishing the absolute stereochemistry of thismaterial.

FIG. 11B illustrates the results of the x-ray crystallographic analysisof(2R,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidep-chlorobenzoate, establishing the absolute stereochemistry of thismaterial, depicted with a numbering scheme for reference.

FIG. 12 illustrates a full chromatogram characterizing fourstereoisomers ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,where the 2S,3R demonstrates a peak at retention time of 5.3 minutes,the 2R,3S demonstrates a peak at retention time of 7.3 minutes, the2R,3R demonstrates a peak at retention time of 8.2 minutes, and the2S,3S demonstrates a retention time of 12.4 minutes. As describedherein, the mobile phase required analysis to provide adequateresolution, resulting in a composition of 60:40:0.2hexanes:ethanol:di-n-butylamine at 1.0 ml/min, with a column temperatureof 20° C., and UV detection at 270 nm.

FIG. 13 is an XRPD of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride illustrating both observed (lighter) and calculated(darker) patterns. Both patterns are in agreement in respect of 2Θvalues and minor difference in intensities and peak widths may beattributed to instrument resolution and preferred orientation effects.As described herein, further minor differences may be attributed to atemperature shift due to the observed data being collected at roomtemperature and calculated data from a structure at 120K.

FIG. 14 is an XRPD of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonotosylate.

DETAILED DESCRIPTION OF THE INVENTION

A specific compound,(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,with affinity (≦1 nM Ki value) and selective for the α7 NNR subtypedemonstrates efficacy in animal models of cognition (cognitiveenhancement) and psychosis (anti-psychotic effects).

One aspect of the present invention is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof. Another aspect is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,in substantially pure form, or a pharmaceutically acceptable saltthereof. A further aspect is(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,substantially free of (2S,3S), (2R,3S), or (2R,3R) isomers, or apharmaceutically acceptable salt thereof.

Further, another aspect is stereoisomerically enriched(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,or a pharmaceutically acceptable salt thereof. In one embodiment, theenantiomeric and/or diastereomeric excess is 90% or greater. In oneembodiment, the enantiomeric and/or diastereomeric excess is 95% orgreater. In one embodiment, the enantiomeric and/or diastereomericexcess is 98% or greater. In one embodiment, the enantiomeric and/ordiastereomeric excess is 99% or greater. In one embodiment, theenantiomeric and/or diastereomeric excess is 99.5% or greater.

Another aspect of the present invention is an acid salt of(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,wherein the acid is selected from hydrochloric acid, sulfuric acid,phosphoric acid, maleic acid, p-toluenesulfonic acid, galactaric (mucic)acid, D-mandelic acid, D-tartaric acid, methanesulfonic acid, R- andS-10-camphorsulfonic acids, ketoglutaric acid, or hippuric acid. In oneembodiment, the stoichiometry of(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideto the acid is 2:1, 1:1, or 1:2. In one embodiment, the stoichiometry is1:1. One embodiment of the present invention is(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehydrochloride or a hydrate or solvate thereof, including partialhydrates or solvates. A further embodiment is(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride or a hydrate or solvate thereof, including partialhydrates or solvates.

Another aspect of the present invention is(2S,3R)-(2-((3-pyridinyl)methyl)-3-amino-1-azabicyclo[2.2.2]octane.

Another aspect of the present invention is a pharmaceutical compositioncomprising a compound of the present invention and one or morepharmaceutically acceptable carrier.

Another aspect of the present invention is a method for treating orpreventing a central nervous system disorder, inflammation, pain, orneovascularization comprising administering a compound of the presentinvention. In one embodiment, the central nervous system disorder ischaracterized by an alteration in normal neurotransmitter release. Inone embodiment, the central nervous system disorder is selected frommild cognitive impairment, age-associated memory impairment, pre-seniledementia, early onset Alzheimer's disease, senile dementia, dementia ofthe Alzheimer's type, Alzheimer's disease, Lewy Body dementia,micro-infarct dementia, AIDS-related dementia, HIV-dementia, multiplecerebral infarcts, Parkinsonism, Parkinson's disease, Pick's disease,progressive supranuclear palsy, Huntington's chorea, tardive dyskinesia,hyperkinesia, mania, attention deficit disorder, attention deficithyperactivity disorder, anxiety, depression, dyslexia, schizophrenia,cognitive dysfunction in schizophrenia, depression, obsessive-compulsivedisorders, or Tourette's syndrome. In one embodiment, the centralnervous system disorder is selected from Alzheimer's disease, mania,attention deficit disorder, attention deficit hyperactivity disorder,anxiety, dyslexia, schizophrenia, cognitive dysfunction inschizophrenia, depression, obsessive-compulsive disorders, or Tourette'ssyndrome.

Another aspect of the present invention includes use of a compound ofthe present invention for the manufacture of a medicament for thetreatment or prevention of a central nervous system disorder,inflammation, pain, or neovascularization. In one embodiment, thecentral nervous system disorder is characterized by an alteration innormal neurotransmitter release. In one embodiment, the central nervoussystem disorder is selected from mild cognitive impairment,age-associated memory impairment, pre-senile dementia, early onsetAlzheimer's disease, senile dementia, dementia of the Alzheimer's type,Alzheimer's disease, Lewy Body dementia, micro-infarct dementia,AIDS-related dementia, HIV-dementia, multiple cerebral infarcts,Parkinsonism, Parkinson's disease, Pick's disease, progressivesupranuclear palsy, Huntington's chorea, tardive dyskinesia,hyperkinesia, mania, attention deficit disorder, attention deficithyperactivity disorder, anxiety, depression, dyslexia, schizophrenia,cognitive dysfunction in schizophrenia, depression, obsessive-compulsivedisorders, or Tourette's syndrome. In one embodiment, the centralnervous system disorder is selected from Alzheimer's disease, mania,attention deficit disorder, attention deficit hyperactivity disorder,anxiety, dyslexia, schizophrenia, cognitive dysfunction inschizophrenia, depression, obsessive-compulsive disorders, or Tourette'ssyndrome.

Another aspect of the present invention is a compound of the presentinvention for use in the treatment or prevention of a central nervoussystem disorder, inflammation, pain, or neovascularization. In oneembodiment, the central nervous system disorder is characterized by analteration in normal neurotransmitter release. In one embodiment, thecentral nervous system disorder is selected from mild cognitiveimpairment, age-associated memory impairment, pre-senile dementia, earlyonset Alzheimer's disease, senile dementia, dementia of the Alzheimer'stype, Alzheimer's disease, Lewy Body dementia, micro-infarct dementia,AIDS-related dementia, HIV-dementia, multiple cerebral infarcts,Parkinsonism, Parkinson's disease, Pick's disease, progressivesupranuclear palsy, Huntington's chorea, tardive dyskinesia,hyperkinesia, mania, attention deficit disorder, attention deficithyperactivity disorder, anxiety, depression, dyslexia, schizophrenia,cognitive dysfunction in schizophrenia, depression, obsessive-compulsivedisorders, or Tourette's syndrome. In one embodiment, the centralnervous system disorder is selected from Alzheimer's disease, mania,attention deficit disorder, attention deficit hyperactivity disorder,anxiety, dyslexia, schizophrenia, cognitive dysfunction inschizophrenia, depression, obsessive-compulsive disorders, or Tourette'ssyndrome.

In the above-mentioned methods and uses, in one embodiment of theinvention the effective does is between about 1 mg and 10 mg per 24-hourperiod.

Another aspect of the present invention is a method for manufacturing(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof by sequential dynamicresolution and stereoselective reductive amination of(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-one.

The scope of the present invention includes all combinations of aspects,embodiments, and preferences herein described.

The commercial development of drug candidates involves many steps,including scaling up the chemical synthesis and purification, findingoptimal salt forms, and the like. In the formulation of drugcompositions, the drug substance is preferably in a form in which it canbe conveniently handled and processed. Considerations include commercialviability as well as consistency in manufacturing. Further, in themanufacture of drug compositions, it is important that a reliable,reproducible and constant plasma concentration profile of drug isprovided following administration to a patient.

Chemical stability, solid state stability, and “shelf life” of theactive ingredients are also very important factors. The drug substance,and compositions containing it, should preferably be capable of beingeffectively stored over appreciable periods of time, without exhibitinga significant change in the active component's physico-chemicalcharacteristics (e.g. its chemical composition, density, hygroscopicityand solubility). Moreover, it is also important to be able to providedrug in a form which is as chemically pure as possible. These featuresof the invention are discussed in more detail below.

I. COMPOUNDS

The compound of the present invention is(2S,3R)—N(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,represented as Compound A below, or a pharmaceutically acceptable saltforms of Compound A.

The racemic compoundN-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,a synthesis, and utility in medical treatment, is described in U.S. Pat.No. 6,953,855 to Mazurov et al, herein incorporated by reference.

RacemicN-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideis a high affinity ligand for the α7 subtype of the neuronal nicotinicreceptor (NNR). RacemicN-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidecontains two asymmetrically substituted carbon atoms. Thus, racemicN-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideoccurs in four stereoisomer forms, namely (S,S), (S,R), (R,R), and(R,S). The (S,R), namely (2S,3R), is Compound A.

Previously, it was believed that the predominant stereoisomeric formsproduced in the reported synthesis, including U.S. Pat. No. 6,953,855,were characterized by the cis relative configuration at the 2 and 3positions of the 1-azabicyclo[2.2.2]octane (quinuclidine) ring. In otherwords, there was an understanding that the cis diastereomer (the (2R,3R)and the (2S,3S) pair of enantiomers), were the predominant forms thatresulted when prepared by the reported methods. This determination, ofpredominantly cis synthesis, was based on: (i) the comparison of ¹Hcoupling constants of the 2 and 3 position hydrogen nuclei of thequinuclidine ring and of the isolated diastereomeric (cis and trans)intermediates to the coupling constants reported in the literature; andon (ii) the expected stereochemical outcome of the synthetic chemistryused to produce the compound mixture, by analogy to the literature, withreference to Warawa et al., J. Med. Chem. 18(6): 587-593 (1975) and Vitiet al., Letrahedron Lett. 35(32): 5939-5942 (1994), both of which areincorporated by reference. Thus, there was an expectation that the cisconfiguration would be formed. As such, the biological testing with theracemate produced results that were presumed attributable to thepredominant cis configuration.

It has now been discovered, via x-ray diffraction analysis ofcrystalline salt forms and analogs, that the predominant diastereomerproduced in the original synthesis was, in fact, the trans diastereomer.Furthermore, it has been discovered that the two enantiomers with thetrans relative stereochemistry, namely the (2S,3R) and the (2R,3S),differ substantially from one another in their ability to interact withthe α7 NNR subtype. The (2S,3R) configuration, Compound A, has greateractivity.

With further analysis, it has been discovered that Compound A haspharmacological properties that distinguish it from: i) each of theother three stereoisomers, taken individually; ii) the mixture of allfour stereoisomers, namely the racemate; and iii) other α7 NNR ligandsreported in the literature.

(2S,3R)—N(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(Compound A) is a highly selective, full agonist at the α7 NNR receptorwith a remarkably low EC₅₀ (for activation) value and a good separationbetween EC₅₀ and the IC₅₀ (for residual inhibition), providingfunctional agonism over a broad range of therapeutically usefulconcentrations.

II. SCALABLE SYNTHESIS OF(2S,3R)—N-(2-((3-PYRIDINYL)METHYL)-1-AZABICYCLO[2.2.2]OCT-3-YL)BENZOFURAN-2-CARBOXAMIDE

Particular synthetic steps vary in their amenability to scale-up.Reactions are found lacking in their ability to be scaled-up for avariety of reasons, including safety concerns, reagent expense,difficult work-up or purification, reaction energetics (thermodynamicsor kinetics), and reaction yield.

The synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidedescribed herein has been used to produce kilogram quantities ofmaterial, and the component reactions have been carried out onmulti-kilogram scale in high yield.

The scalable synthesis utilizes both the dynamic resolution of aracemizable ketone(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one) and thestereoselective reduction of the (R)-α-methylbenzylamine iminederivative (reductive amination) of the resolved ketone.

The synthetic sequences reported herein are readily scalable and avoidchromatographic purifications.

III. PREPARATION OF NOVEL SALT FORMS OF(2S,3R)—N-(2-((3-PYRIDINYL)METHYL-1-AZABICYCLO[2.2.2]OCT-3-YL)BENZOFURAN-2-CARBOXAMIDE

(2S,3R)—N-(2-((3-Pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideas a free base is an amorphous powder with very limited watersolubility. The free base will react with both inorganic and organicacids to make certain acid addition salts that have physical andchemical properties that are advantageous for the preparation ofpharmaceutical compositions, including but not limited to crystallinity,water solubility, and stability. The stoichiometry of the salts of thepresent invention can vary.

Depending upon the manner by which the salts described herein areformed, the salts can have crystal structures that occlude solvents thatare present during salt formation. Thus, the salts can occur as hydratesand other solvates of varying stoichiometry of solvent relative to the(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide.

The method for preparing the salt forms can vary. The preparation of(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidesalt forms generally involves:

(i) mixing the free base or a solution of the free base, namely(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidein a suitable solvent with an acid neat, or as a solution of an acids ina suitable solvent;(iia) cooling the resulting salt solution, if necessary to causeprecipitation; or(iib) adding a suitable anti-solvent to cause precipitation; or(iic) evaporating the first solvent and adding a new solvent andrepeating either steps (iia) or step (iib); and(iii) filtering and collecting the resulting salt.

In one embodiment, the(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideis stereoisomerically enriched. In one embodiment, the enantiomericand/or diastereomeric excess is 90% or greater. In one embodiment, theenantiomeric and/or diastereomeric excess is 95% or greater. In oneembodiment, the enantiomeric and/or diastereomeric excess is 98% orgreater. In one embodiment, the enantiomeric and/or diastereomericexcess is 99% or greater. In one embodiment, the enantiomeric and/ordiastereomeric excess is 99.5% or greater.

The stoichiometry, solvent mix, solute concentration, and temperatureemployed can vary. Representative solvents that can be used to prepareor recrystallize the salt forms include, without limitation, ethanol,methanol, isopropyl alcohol, acetone, ethyl acetate, and acetonitrile.

Examples of suitable pharmaceutically acceptable salts include inorganicacid addition salts such as chloride, bromide, sulfate, phosphate, andnitrate; organic acid addition salts such as acetate, galactarate,propionate, succinate, lactate, glycolate, malate, tartrate, citrate,maleate, fumarate, methanesulfonate, p-toluenesulfonate, and ascorbate;and salts with amino acids such as aspartate and glutamate. The saltsmay be in some cases hydrates or ethanol solvates. Representative saltsare provided as described in U.S. Pat. Nos. 5,597,919 to Dull et al.,5,616,716 to Dull et al. and 5,663,356 to Ruecroft et al, each of whichis incorporated by reference.

Salt screening for the free base(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamiderevealed that, while many salts of pharmaceutically acceptable acidscould be formed, only a few of these salts had acceptable properties forcommercial manufacture. The ability to predict the characteristicsexemplified by a commercially viable salt, therefore, does not exist.Acids that provided salts that were crystalline, namely salts thatdemonstrate some degree of crystallinity, dependent upon the method bywhich they are prepared, include hydrochloric acid, sulfuric acid,phosphoric acid, p-toluenesulfonic acid, galactaric (mucic) acid,D-mandelic acid, D-tartaric acid, methanesulfonic acid, R- andS-10-camphorsulfonic acids, maleic acid, ketoglutaric acid and hippuricacid. Of these salts, the hydrochloric acid, phosphoric acid, maleicacid and p-toluenesulfonic acid salts each exhibited additionaldesirable properties, including high melting points, good watersolubility, and low hygroscopicity. These characteristics in these saltswere unexpected.

IV. PHARMACEUTICAL COMPOSITIONS

The pharmaceutical compositions of the present invention include thesalts described herein, in the pure state or in the form of acomposition in which the compounds are combined with any otherpharmaceutically compatible product, which can be inert orphysiologically active. The resulting pharmaceutical compositions can beused to prevent a condition or disorder in a subject susceptible to sucha condition or disorder, and/or to treat a subject suffering from thecondition or disorder. The pharmaceutical compositions described hereininclude the compound of the present invention and/or pharmaceuticallyacceptable salts thereof.

The manner in which the compounds are administered can vary. Thecompositions are preferably administered orally (e.g., in liquid formwithin a solvent such as an aqueous or non-aqueous liquid, or within asolid carrier). Preferred compositions for oral administration includepills, tablets, capsules, caplets, syrups, and solutions, including hardgelatin capsules and time-release capsules. Standard excipients includebinders, fillers, colorants, solubilizers, and the like. Compositionscan be formulated in unit dose form, or in multiple or subunit doses.Preferred compositions are in liquid or semisolid form. Compositionsincluding a liquid pharmaceutically inert carrier such as water or otherpharmaceutically compatible liquids or semisolids can be used. The useof such liquids and semisolids is well known to those of skill in theart.

The compositions can also be administered via injection, i.e.,intravenously, intramuscularly, subcutaneously, intraperitoneally,intraarterially, intrathecally; and intracerebroventricularly.Intravenous administration is the preferred method of injection.Suitable carriers for injection are well known to those of skill in theart and include 5% dextrose solutions, saline, and phosphate-bufferedsaline. The drug product can also be administered as an infusion orinjection (e.g., as a suspension or as an emulsion in a pharmaceuticallyacceptable liquid or mixture of liquids).

The formulations can also be administered using other means, forexample, rectal administration. Formulations useful for rectaladministration, such as suppositories, are well known to those of skillin the art. The drug product can also be administered by inhalation(e.g., in the form of an aerosol either nasally or using deliveryarticles of the type set forth in U.S. Pat. No. 4,922,901 to Brooks etal., the disclosure of which is incorporated herein in its entirety);topically (e.g., in lotion form); transdermally (e.g., using atransdermal patch) or iontophoretically; or by sublingual or buccaladministration. Although it is possible to administer a compound in theform of a bulk active chemical, it is preferred to present a drugproduct in the form of a pharmaceutical composition or formulation forefficient and effective administration.

Exemplary methods for administering compounds will be apparent to theskilled artisan. The usefulness of these formulations can depend on theparticular composition used and the particular subject receiving thetreatment. These formulations can contain a liquid carrier that can beoily, aqueous, emulsified or contain certain solvents suitable to themode of administration.

The compositions can be administered intermittently or at a gradual,continuous, constant or controlled rate to a warm-blooded animal (e.g.,a mammal such as a mouse, rat, cat, rabbit, dog, pig, cow, or monkey),but advantageously are administered to a human being. In addition, thetime of day and the number of times per day that the pharmaceuticalformulation is administered can vary.

Other suitable methods for administering the compounds of the presentinvention are described in U.S. Pat. No. 5,604,231 to Smith et al., thecontents of which are hereby incorporated by reference.

In an embodiment of the present invention and as will be appreciated bythose skilled in the art, the compound of the present invention may beadministered in combination with other therapeutic compounds. Forexample, a compound of this invention can be used in combination withother NNR ligands (such as varenicline), antioxidants (such as freeradical scavenging agents), antibacterial agents (such as penicillinantibiotics), antiviral agents (such as nucleoside analogs, likezidovudine and acyclovir), anticoagulants (such as warfarin),anti-inflammatory agents (such as NSAIDs), anti-pyretics, analgesics,anesthetics (such as used in surgery), acetylcholinesterase inhibitors(such as donepezil and galantamine), antipsychotics (such ashaloperidol, clozapine, olanzapine, and quetiapine), immuno-suppressants(such as cyclosporin and methotrexate), neuroprotective agents, steroids(such as steroid hormones), corticosteroids (such as dexamethasone,predisone, and hydrocortisone), vitamins, minerals, nutraceuticals,anti-depressants (such as imipramine, fluoxetine, paroxetine,escitalopram, sertraline, venlafaxine, and duloxetine), anxiolytics(such as alprazolam and buspirone), anticonvulsants (such as phenyloinand gabapentin), vasodilators (such as prazosin and sildenafil), moodstabilizers (such as valproate and aripiprazole), anti-cancer drugs(such as anti-proliferatives), antihypertensive agents (such asatenolol, clonidine, amlopidine, verapamil, and olmesartan), laxatives,stool softeners, diuretics (such as furosemide), anti-spasmotics (suchas dicyclomine), anti-dyskinetic agents, and anti-ulcer medications(such as esomeprazole).

The compounds of the present invention may be employed alone or incombination with other therapeutic agents. Such a combination ofpharmaceutically active agents may be administered together orseparately and, when administered separately, administration may occursimultaneously or sequentially, in any order. The amounts of thecompounds or agents and the relative timings of administration will beselected in order to achieve the desired therapeutic effect. Theadministration in combination may be by administration concomitantly in:(1) a unitary pharmaceutical composition including multiple compounds;or (2) separate pharmaceutical compositions each including one of thecompounds. Alternatively, the combination may be administered separatelyin a sequential manner wherein one treatment agent is administered firstand the other second or vice versa. Such sequential administration maybe close in time or remote in time. The compounds of the presentinvention may be used in the treatment of a variety of disorders andconditions and, as such, the compounds of the present invention may beused in combination with a variety of other suitable therapeutic agentsuseful in the treatment or prophylaxis of those disorders or conditions.

The appropriate dose of the compound is that amount effective to preventoccurrence of the symptoms of the disorder or to treat some symptoms ofthe disorder from which the patient suffers. As noted, by “effectiveamount”, “therapeutic amount” or “effective dose” is meant that amountsufficient to elicit the desired pharmacological or therapeutic effects,thus resulting in effective prevention or treatment of the disorder.

When treating a CNS disorder, an effective amount of compound is anamount sufficient to pass across the blood-brain barrier of the subject,to bind to relevant receptor sites in the brain of the subject and tomodulate the activity of relevant NNR subtypes (e.g., provideneurotransmitter secretion, thus resulting in effective prevention ortreatment of the disorder). An example of prevention of a disorder ismanifested by delaying the onset of the symptoms of the disorder. Anexample of treatment of a disorder is manifested by a decrease in thesymptoms associated with the disorder or an amelioration of therecurrence of the symptoms of the disorder. Preferably, the effectiveamount is sufficient to obtain the desired result, but insufficient tocause appreciable side effects.

The effective dose can vary, depending upon factors such as thecondition of the patient, the severity of the symptoms of the disorder,and the manner in which the pharmaceutical composition is administered.For human patients, the effective dose of typical compounds generallyrequires administering the compound in an amount sufficient to modulatethe activity of relevant NNRs, but the amount should be insufficient toinduce effects on skeletal muscles and ganglia to any significantdegree. The effective dose of compounds will of course differ frompatient to patient, but in general includes amounts starting where CNSeffects or other desired therapeutic effects occur but below the amountwhere muscular effects are observed.

The compounds described herein, when employed in effective amounts inaccordance with the methods described herein, can provide some degree ofprevention of the progression of, ameliorate symptoms of, or ameliorate,to some degree, the recurrence of CNS or other disorders. The effectiveamounts of those compounds are typically below the thresholdconcentration required to elicit any appreciable side effects, forexample those effects relating to skeletal muscle or ganglia. Thecompounds can be administered in a therapeutic window in which certainCNS and other disorders are treated and certain side effects areavoided. Ideally, the effective dose of the compounds described hereinis sufficient to provide the desired effects upon the disorder but isinsufficient (i.e., is not at a high enough level) to provideundesirable side effects. Preferably, the compounds are administered ata dosage effective for treating the CNS or other disorders but lessthan, often less than ⅕, and often less than 1/10, the amount requiredto elicit certain side effects to any significant degree.

Most preferably, effective doses are at very low concentrations, wheremaximal effects are observed to occur, with a minimum of side effects.Typically, the effective dose of such compounds generally requiresadministering the compound in an amount of less than 5 mg/kg of patientweight. Often, the compounds of the present invention are administeredin an amount from less than about 1 mg/kg patient weight and usuallyless than about 100 μg/kg of patient weight, but frequently betweenabout 10 μg to less than 100 μg/kg of patient weight. The foregoingeffective doses typically represent that amount administered as a singledose, or as one or more doses administered over a 24-hour period.

For human patients, the effective dose of typical compounds generallyrequires administering the compound in an amount of at least about 1,often at least about 10, and frequently at least about 100 mg/24hr/patient. For human patients, the effective dose of typical compoundsrequires administering the compound which generally does not exceedabout 500, often does not exceed about 400, and frequently does notexceed about 300 mg/24 hr/patient. In addition, the compositions areadvantageously administered at an effective dose such that theconcentration of the compound within the plasma of the patient normallydoes not exceed 50 ng/mL, often does not exceed 30 ng/mL, and frequentlydoes not exceed 10 ng/mL. In one embodiment of the present invention, aneffective dose is between about 1 mg and 10 mg in a 24-hour period.

IV. METHOD OF USING PHARMACEUTICAL COMPOSITIONS

As used herein, an “agonist” is a substance that stimulates its bindingpartner, typically a receptor. Stimulation is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Stimulation may be defined with respect to anincrease in a particular effect or function that is induced byinteraction of the agonist or partial agonist with a binding partner andcan include allosteric effects.

As used herein, an “antagonist” is a substance that inhibits its bindingpartner, typically a receptor. Inhibition is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Inhibition may be defined with respect to adecrease in a particular effect or function that is induced byinteraction of the antagonist with a binding partner, and can includeallosteric effects.

As used herein, a “partial agonist” or a “partial antagonist” is asubstance that provides a level of stimulation or inhibition,respectively, to its binding partner that is not fully or completelyagonistic or antagonistic, respectively. It will be recognized thatstimulation, and hence, inhibition is defined intrinsically for anysubstance or category of substances to be defined as agonists,antagonists, or partial agonists.

As used herein, “intrinsic activity” or “efficacy” relates to somemeasure of biological effectiveness of the binding partner complex. Withregard to receptor pharmacology, the context in which intrinsic activityor efficacy should be defined will depend on the context of the bindingpartner (e.g., receptor/ligand) complex and the consideration of anactivity relevant to a particular biological outcome. For example, insome circumstances, intrinsic activity may vary depending on theparticular second messenger system involved. See Hoyer, D. and Boddeke,H., Trends Pharmacol. Sci. 14(7): 270-5 (1993), herein incorporated byreference with regard to such teaching. Where such contextually specificevaluations are relevant, and how they might be relevant in the contextof the present invention, will be apparent to one of ordinary skill inthe art.

As used herein, modulation of a receptor includes agonism, partialagonism, antagonism, partial antagonism, or inverse agonism of areceptor.

As used herein, neurotransmitters whose release is mediated by thecompounds described herein include, but are not limited to,acetylcholine, dopamine, norepinephrine, serotonin, and glutamate, andthe compounds described herein function as modulators at the α7 subtypeof the CNS NNRs.

As used herein, the terms “prevention” or “prophylaxis” include anydegree of reducing the progression of or delaying the onset of adisease, disorder, or condition. The term includes providing protectiveeffects against a particular disease, disorder, or condition as well asamelioration of the recurrence of the disease, disorder, or condition.Thus, in another aspect, the invention provides a method for treating asubject having or at risk of developing or experiencing a recurrence ofa NNR or nAChR mediated disorder. The compounds and pharmaceuticalcompositions of the invention may be used to achieve a beneficialtherapeutic or prophylactic effect, for example, in a subject with a CNSdysfunction.

As noted above, the free base and salt compounds of the presentinvention modulates the α7 NNR subtype, characteristic of the CNS, andcan be used for preventing or treating various conditions or disorders,including those of the CNS, in subjects which have or are susceptible tosuch conditions or disorders, by modulation of the α7 NNR. The compoundshave the ability to selectively bind to the α7 NNR and express nicotinicpharmacology, for example, to act as agonists, partial agonists,antagonists, as described.

For example, compounds of the present invention, when administered ineffective amounts to patients in need thereof, provide some degree ofprevention of the progression of the CNS disorder, namely, providingprotective effects, amelioration of the symptoms of the CNS disorder, oramelioration of the reoccurrence of the CNS disorder, or a combinationthereof.

The compounds of the present invention can be used to treat or preventthose types of conditions and disorders for which other types ofnicotinic compounds have been proposed or are shown to be useful astherapeutics. See, for example, the references previously listedhereinabove, as well as Williams et al., Drug News Perspec. 7(4): 205(1994), Arneric et al., CNS Drug Rev. 1(1): 1-26 (1995), Arneric et al.,Exp. Opin. Invest. Drugs 5(1): 79-100 (1996), Bencherif et al., J.Pharmacol. Exp. Ther. 279: 1413 (1996), Lippiello et al., J. Pharmacol.Exp. Ther. 279: 1422 (1996), Damaj et al., J. Pharmacol. Exp. Ther. 291:390 (1999); Chiari et al., Anesthesiology 91: 1447 (1999), Lavand'hommeand Eisenbach, Anesthesiology 91: 1455 (1999), Holladay et al., J. Med.Chem. 40(28): 4169-94 (1997), Bannon et al., Science 279: 77 (1998), PCTWO 94/08992, PCT WO 96/31475, PCT WO 96/40682, and U.S. Pat. Nos.5,583,140 to Bencherif et al., 5,597,919 to Dull et al., 5,604,231 toSmith et al. and 5,852,041 to Cosford et al., the disclosures of whichare incorporated herein by reference with regard to such therapeuticteaching.

The compounds and their pharmaceutical compositions are useful in thetreatment or prevention of a variety of CNS disorders, includingneurodegenerative disorders, neuropsychiatric disorders, neurologicdisorders, and addictions. The compounds and their pharmaceuticalcompositions can be used to treat or prevent cognitive deficits anddysfunctions, age-related and otherwise; attentional disorders anddementias, including those due to infectious agents or metabolicdisturbances; to provide neuroprotection; to treat convulsions andmultiple cerebral infarcts; to treat mood disorders, compulsions andaddictive behaviors; to provide analgesia; to control inflammation, suchas mediated by cytokines and nuclear factor kappa B; to treatinflammatory disorders; to provide pain relief; to treat metabolicdisorders such as diabetes or metabolic syndrome; and to treatinfections, as anti-infectious agents for treating bacterial, fungal,and viral infections.

CNS Disorders

Among the disorders, diseases and conditions that the compounds andpharmaceutical compositions of the present invention can be used totreat or prevent are: age-associated memory impairment (AAMI), mildcognitive impairment (MCI), age-related cognitive decline (ARCD),pre-senile dementia, early onset Alzheimer's disease, senile dementia,dementia of the Alzheimer's type, Alzheimer's disease, cognitiveimpairment no dementia (CIND), Lewy body dementia, HIV-dementia, AIDSdementia complex, vascular dementia, Down syndrome, head trauma,traumatic brain injury (TBI), dementia pugilistica, Creutzfeld-JacobDisease and prion diseases, stroke, ischemia, attention deficitdisorder, attention deficit hyperactivity disorder, dyslexia,schizophrenia, schizophreniform disorder, schizoaffective disorder,cognitive dysfunction in schizophrenia, cognitive deficits inschizophrenia such as memory, including working memory, executivefunction, attention, vigilance, information processing, and learning,dementia (whether mild, moderate or severe) associated withschizophrenia, dementia (whether mild, moderate or severe) associatedwith schizophrenia, Parkinsonism including Parkinson's disease,postencephalitic parkinsonism, parkinsonism-dementia of Gaum,frontotemporal dementia Parkinson's Type (FTDP), Pick's disease,Niemann-Pick's Disease, Huntington's Disease, Huntington's chorea,tardive dyskinesia, hyperkinesia, progressive supranuclear palsy,progressive supranuclear paresis, restless leg syndrome, multiplesclerosis, amyotrophic lateral sclerosis (ALS), motor neuron diseases(MND), multiple system atrophy (MSA), corticobasal degeneration,Guillain-Barré Syndrome (GBS), chronic inflammatory demyelinatingpolyneuropathy (CIDP), epilepsy, autosomal dominant nocturnal frontallobe epilepsy, mania, anxiety, depression, premenstrual dysphoria, panicdisorders, bulimia, anorexia, narcolepsy, excessive daytime sleepiness,bipolar disorders, generalized anxiety disorder, obsessive compulsivedisorder, rage outbursts, oppositional defiant disorder, Tourette'ssyndrome, autism, drug and alcohol addiction, tobacco addiction,obesity, cachexia, psoriasis, lupus, acute cholangitis, aphthousstomatitis, ulcers, asthma, ulcerative colitis, inflammatory boweldisease, Crohn's disease, post operative ileus, spastic dystonia,diarrhea, constipation, pouchitis, pancreatitis, viral pneumonitis,arthritis, including, rheumatoid arthritis and osteoarthritis,endotoxaemia, sepsis, atherosclerosis, idiopathic pulmonary fibrosis,acute pain, chronic pain, neuropathies, urinary incontinence, diabetes,and neoplasias.

Cognitive impairments or dysfunctions may be associated with psychiatricdisorders or conditions, such as schizophrenia and other psychoticdisorders, including but not limited to psychotic disorder,schizophreniform disorder, schizoaffective disorder, delusionaldisorder, brief psychotic disorder, shared psychotic disorder, andpsychotic disorders due to one or more general medical conditions,dementias, and other cognitive disorders, including but not limited tomild cognitive impairment, pre-senile dementia, Alzheimer's disease,senile dementia, dementia of the Alzheimer's type, age-related memoryimpairment, Lewy body dementia, vascular dementia, AIDS dementiacomplex, dyslexia, Parkinsonism including Parkinson's disease, cognitiveimpairment and dementia of Parkinson's Disease, cognitive impairment ofmultiple sclerosis, cognitive impairment caused by traumatic braininjury, dementias due to other general medical conditions, anxietydisorders, including but not limited to panic disorder withoutagoraphobia, panic disorder with agoraphobia, agoraphobia withouthistory of panic disorder, specific phobia, social phobia,obsessive-compulsive disorder, post-traumatic stress disorder, acutestress disorder, generalized anxiety disorder and generalized anxietydisorder due to a general medical condition, mood disorders, includingbut not limited to major depressive disorder, dysthymic disorder,bipolar depression, bipolar mania, bipolar I disorder, depressionassociated with manic, depressive or mixed episodes, bipolar IIdisorder, cyclothymic disorder, and mood disorders due to generalmedical conditions, sleep disorders, including but not limited todyssomnia disorders, primary insomnia, primary hypersomnia, narcolepsy,parasomnia disorders, nightmare disorder, sleep terror disorder andsleepwalking disorder, mental retardation, learning disorders, motorskills disorders, communication disorders, pervasive developmentaldisorders, attention-deficit and disruptive behavior disorders,attention deficit disorder, attention deficit hyperactivity disorder,feeding and eating disorders of infancy, childhood, or adults, ticdisorders, elimination disorders, substance-related disorders, includingbut not limited to substance dependence, substance abuse, substanceintoxication, substance withdrawal, alcohol-related disorders,amphetamine or amphetamine-like-related disorders, caffeine-relateddisorders, cannabis-related disorders, cocaine-related disorders,hallucinogen-related disorders, inhalant-related disorders,nicotine-related disorders, opioid-related disorders, phencyclidine orphencyclidine-like-related disorders, and sedative-, hypnotic- oranxiolytic-related disorders, personality disorders, including but notlimited to obsessive-compulsive personality disorder and impulse-controldisorders.

The symptoms of schizophrenia are generally divided into threecategories: Positive, Negative, and Cognitive. Positive Symptoms, mayalso be referred to as “psychotic” symptoms, and include delusions andhallucinations. “Positive” refers to having overt symptoms. NegativeSymptoms include emotional flatness or lack of expression, an inabilityto start and follow through with activities, speech that is brief anddevoid of content, and a lack of pleasure or interest in activities.“Negative” refers to a lack of certain characteristics that wouldotherwise be present in a healthy individual. Cognitive Symptoms pertainto thinking processes. Cognitive symptoms include cognitive deficitssuch as memory, including working memory, executive function, attention,vigilance, information processing, and learning, with reference toSharma et al., Cognitive Function in Schizophrenia: Deficits, FunctionalConsequences, and Future Treatment, Psychiatr. Clin. N. Am. 26 (2003)25-40, herein incorporated by reference. Schizophrenia also affectsmood. While many individuals affected with schizophrenia becomedepressed, some also have apparent mood swings and even bipolar-likestates.

The above conditions and disorders are discussed in further detail, forexample, in the American Psychiatric Association: Diagnostic andStatistical Manual of Mental Disorders, Fourth Edition, Text Revision,Washington, D.C., American Psychiatric Association, 2000; incorporatedherein by reference with regard to defining such conditions anddisorders. This Manual may also be referred to for greater detail on thesymptoms and diagnostic features associated with substance use, abuse,and dependence.

Preferably, the treatment or prevention of diseases, disorders, andconditions occurs without appreciable adverse side effects, including,for example, significant increases in blood pressure and heart rate,significant negative effects upon the gastro-intestinal tract, andsignificant effects upon skeletal muscle.

The compounds of the present invention, when employed in effectiveamounts, are believed to modulate the activity of the α7 NNR withoutappreciable interaction with the nicotinic subtypes that characterizethe human ganglia, as demonstrated by a lack of the ability to elicitnicotinic function in adrenal chromaffin tissue, or skeletal muscle,further demonstrated by a lack of the ability to elicit nicotinicfunction in cell preparations expressing muscle-type nicotinicreceptors. Thus, these compounds are believed capable of treating orpreventing diseases, disorders, and conditions without elicitingsignificant side effects associated activity at ganglionic andneuromuscular sites. Thus, administration of the compounds is believedto provide a therapeutic window in which treatment of certain diseases,disorders, and conditions is provided, and certain side effects areavoided. That is, an effective dose of the compound is believedsufficient to provide the desired effects upon the disease, disorder, orcondition, but is believed insufficient, namely is not at a high enoughlevel, to provide undesirable side effects.

Thus, the present invention provides the use of a compound of thepresent invention, or a pharmaceutically acceptable salt thereof, foruse in therapy, such as a therapy described above.

In yet another aspect the present invention provides the use of acompound of the present invention, or a pharmaceutically acceptable saltthereof, in the manufacture of a medicament for use in the treatment ofa CNS disorder, such as a disorder, disease or condition describedhereinabove.

Inflammation

The nervous system, primarily through the vagus nerve, is known toregulate the magnitude of the innate immune response by inhibiting therelease of macrophage tumor necrosis factor (TNF). This physiologicalmechanism is known as the “cholinergic anti-inflammatory pathway” (see,for example, Tracey, “The inflammatory reflex,” Nature 420: 853-9(2002), herein incorporated by reference). Excessive inflammation andtumor necrosis factor synthesis cause morbidity and even mortality in avariety of diseases. These diseases include, but are not limited to,endotoxemia, rheumatoid arthritis, osteoarthritis, psoriasis, asthma,atherosclerosis, idiopathic pulmonary fibrosis, and inflammatory boweldisease.

Inflammatory conditions that can be treated or prevented byadministering the compounds described herein include, but are notlimited to, chronic and acute inflammation, psoriasis, endotoxemia,gout, acute pseudogout, acute gouty arthritis, arthritis, rheumatoidarthritis, osteoarthritis, polymyositis, dermatomyositis, ankylosingspondylitis, Still's disease, adult onset Still's disease, allograftrejection, chronic transplant rejection, asthma, atherosclerosis,mononuclear-phagocyte dependent lung injury, idiopathic pulmonaryfibrosis, atopic dermatitis, chronic obstructive pulmonary disease,adult respiratory distress syndrome, acute chest syndrome in sickle celldisease, inflammatory bowel disease, Crohn's disease, ulcerativecolitis, acute cholangitis, aphteous stomatitis, pouchitis,glomerulonephritis, lupus nephritis, thrombosis, and graft vs. hostreaction.

Inflammatory Response Associated with Bacterial and/or Viral Infection

Many bacterial and/or viral infections (e.g., meningitis, hepatitis andnephritis) are associated with side effects brought on by the formationof toxins, and the body's natural response to the bacteria or virusand/or the toxins. As discussed above, the body's response to infectionoften involves generating a significant amount of TNF and/or othercytokines. The over-expression of these cytokines can result insignificant injury, such as septic shock (when the bacteria is sepsis),endotoxic shock, urosepsis, and toxic shock syndrome.

Cytokine expression is mediated by NNRs, and can be inhibited byadministering agonists or partial agonists of these receptors. Thosecompounds described herein that are agonists or partial agonists ofthese receptors can therefore be used to minimize the inflammatoryresponse associated with bacterial infection, as well as viral andfungal infections. Examples of such bacterial infections includeanthrax, botulism, and sepsis. Some of these compounds may also haveantimicrobial properties.

These compounds can also be used as adjunct therapy in combination withexisting therapies to manage bacterial, viral, and fungal infections,such as antibiotics, antivirals, and antifungals. Antitoxins can also beused to bind to toxins produced by the infectious agents and allow thebound toxins to pass through the body without generating an inflammatoryresponse. Examples of antitoxins are disclosed, for example, in U.S.Pat. No. 6,310,043 to Bundle et al., incorporated herein by reference.Other agents effective against bacterial and other toxins can beeffective and their therapeutic effect can be complemented byco-administration with the compounds described herein.

Pain

The compounds can be administered to treat and/or prevent pain,including acute, neurologic, inflammatory, neuropathic, and chronicpain. The analgesic activity of compounds described herein can bedemonstrated in models of persistent inflammatory pain and ofneuropathic pain, performed as described in U.S. Published PatentApplication No. 20010056084 A1 (Allgeier et al.), incorporated byreference, wherein is demonstrated hyperalgesia in the complete Freund'sadjuvant rat model of inflammatory pain and mechanical hyperalgesia inthe mouse partial sciatic nerve ligation model of neuropathic pain.

The analgesic effect is suitable for treating pain of various genesis oretiology, in particular in treating inflammatory pain and associatedhyperalgesia, neuropathic pain, and associated hyperalgesia, chronicpain (e.g., severe chronic pain, post-operative pain, and painassociated with various conditions including cancer, angina, renal orbiliary colic, menstruation, migraine, and gout). Inflammatory pain maybe of diverse genesis, including arthritis and rheumatoid disease,teno-synovitis, and vasculitis. Neuropathic pain includes trigeminal orherpetic neuralgia, diabetic neuropathy pain, causalgia, low back pain,and deafferentation syndromes such as brachial plexus avulsion.

Neovascularization

The α7 NNR is associated with neovascularization. Inhibition ofneovascularization, for example, by administering antagonists (or atcertain dosages, partial agonists) of the α7 NNR can treat or preventconditions characterized by undesirable neovascularization orangiogenesis. Such conditions can include those characterized byinflammatory angiogenesis and/or ischemia-induced angiogenesis.Neovascularization associated with tumor growth can also be inhibited byadministering those compounds described herein that function asantagonists or partial agonists of α7 NNR.

Specific antagonism of α7 NNR-specific activity reduces the angiogenicresponse to inflammation, ischemia, and neoplasia. Guidance regardingappropriate animal model systems for evaluating the compounds describedherein can be found, for example, in Heeschen, C. et al., “A novelangiogenic pathway mediated by non-neuronal nicotinic acetylcholinereceptors,” J. Clin. Invest 110(4):527-36 (2002), incorporated herein byreference regarding disclosure of α7-specific inhibition of angiogenesisand cellular (in vitro) and animal modeling of angiogenic activityrelevant to human disease, especially the Lewis lung tumor model (invivo, in mice—see, in particular, pages 529, and 532-533).

Representative tumor types that can be treated using the compoundsdescribed herein include NSCLC, ovarian cancer, pancreatic cancer,breast carcinoma, colon carcinoma, rectum carcinoma, lung carcinoma,oropharynx carcinoma, hypopharynx carcinoma, esophagus carcinoma,stomach carcinoma, pancreas carcinoma, liver carcinoma, gallbladdercarcinoma, bile duct carcinoma, small intestine carcinoma, urinary tractcarcinoma, kidney carcinoma, bladder carcinoma, urothelium carcinoma,female genital tract carcinoma, cervix carcinoma, uterus carcinoma,ovarian carcinoma, choriocarcinoma, gestational trophoblastic disease,male genital tract carcinoma, prostate carcinoma, seminal vesiclescarcinoma, testes carcinoma, germ cell tumors, endocrine glandcarcinoma, thyroid carcinoma, adrenal carcinoma, pituitary glandcarcinoma, skin carcinoma, hemangiomas, melanomas, sarcomas, bone andsoft tissue sarcoma, Kaposi's sarcoma, tumors of the brain, tumors ofthe nerves, tumors of the eyes, tumors of the meninges, astrocytomas,gliomas, glioblastomas, retinoblastomas, neuromas, neuroblastomas,Schwannomas, meningiomas, solid tumors arising from hematopoieticmalignancies (such as leukemias, chloromas, plasmacytomas, and theplaques and tumors of mycosis fungoides and cutaneous T-celllymphoma/leukemia), and solid tumors arising from lymphomas.

The compounds can also be administered in conjunction with other formsof anti-cancer treatment, including co-administration withantineoplastic antitumor agents such as cis-platin, adriamycin,daunomycin, and the like, and/or anti-VEGF (vascular endothelial growthfactor) agents, as such are known in the art.

The compounds can be administered in such a manner that they aretargeted to the tumor site. For example, the compounds can beadministered in microspheres, microparticles or liposomes conjugated tovarious antibodies that direct the microparticles to the tumor.Additionally, the compounds can be present in microspheres,microparticles or liposomes that are appropriately sized to pass throughthe arteries and veins, but lodge in capillary beds surrounding tumorsand administer the compounds locally to the tumor. Such drug deliverydevices are known in the art.

Other Disorders

In addition to treating CNS disorders, inflammation, neovascularization,and pain, the compounds of the present invention can be also used toprevent or treat certain other conditions, diseases, and disorders inwhich NNRs play a role. Examples include autoimmune disorders such asLupus, disorders associated with cytokine release, cachexia secondary toinfection (e.g., as occurs in AIDS, AIDS related complex and neoplasia),metabolic disorders, including type I diabetes, type II diabetes,metabolic syndrome, obesity, or hyperglycemia, pemphitis, urinaryincontinence, retinal diseases, infectious diseases, myasthenia,Eaton-Lambert syndrome, hypertension, osteoporosis, vasoconstriction,vasodilatation, cardiac arrhythmias, bulimia, anorexia as well as thoseindications set forth in published PCT application WO 98/25619, hereinincorporated by reference with regard to such disorders. The compoundsof this invention can also be administered to treat convulsions such asthose that are symptomatic of epilepsy, and to treat conditions such assyphilis and Creutzfeld-Jakob disease.

Diagnostic Uses

The compounds can be used in diagnostic compositions, such as probes,particularly when they are modified to include appropriate labels. Theprobes can be used, for example, to determine the relative number and/orfunction of specific receptors, particularly the α7 receptor subtype.For this purpose the compounds of the present invention most preferablyare labeled with a radioactive isotopic moiety such as ¹¹C, ¹⁸F, ⁷⁶Br,¹²³I or ¹²⁵I.

The administered compounds can be detected using known detection methodsappropriate for the label used. Examples of detection methods includeposition emission topography (PET) and single-photon emission computedtomography (SPECT). The radiolabels described above are useful in PET(e.g., ¹¹C, ¹⁸F or ⁷⁶Br) and SPECT (e.g., ¹²³I) imaging, with half-livesof about 20.4 minutes for ¹¹C, about 109 minutes for ¹⁸F, about 13 hoursfor ¹²³I, and about 16 hours for ⁷⁶Br. A high specific activity isdesired to visualize the selected receptor subtypes at non-saturatingconcentrations. The administered doses typically are below the toxicrange and provide high contrast images. The compounds are expected to becapable of administration in non-toxic levels. Determination of dose iscarried out in a manner known to one skilled in the art of radiolabelimaging. See, for example, U.S. Pat. No. 5,969,144 to London et al.,incorporated herein by reference with regard to administration of suchcompounds.

The compounds can be administered using known techniques. See, forexample, U.S. Pat. No. 5,969,144 to London et al., as noted,incorporated by reference with regard to such administration. Thecompounds can be administered in formulation compositions thatincorporate other ingredients, such as those types of ingredients thatare useful in formulating a diagnostic composition. Compounds useful inaccordance with carrying out the present invention most preferably areemployed in forms of high purity. See, U.S. Pat. No. 5,853,696 toElmalch et al., herein incorporated by reference with regard to suchanalysis.

After the compounds are administered to a subject (e.g., a humansubject), the presence of that compound within the subject can be imagedand quantified by appropriate techniques in order to indicate thepresence, quantity, and functionality of selected NNR subtypes. Inaddition to humans, the compounds can also be administered to animals,such as mice, rats, dogs, and monkeys. SPECT and PET imaging can becarried out using any appropriate technique and apparatus. SeeVillemagne et al., In: Arneric et al. (Eds.) Neuronal NicotinicReceptors: Pharmacology and Therapeutic Opportunities, 235-250 (1998)and U.S. Pat. No. 5,853,696 to Elmalch et al., each herein incorporatedby reference, for a disclosure of representative imaging techniques.

The radiolabeled compounds bind with high affinity to selective NNRsubtypes (e.g., α7) and preferably exhibit negligible non-specificbinding to other nicotinic cholinergic receptor subtypes (e.g., thosereceptor subtypes associated with muscle and ganglia). As such, thecompounds can be used as agents for noninvasive imaging of nicotiniccholinergic receptor subtypes within the body of a subject, particularlywithin the brain for diagnosis associated with a variety of CNS diseasesand disorders.

In one aspect, the diagnostic compositions can be used in a method todiagnose disease in a subject, such as a human patient. The methodinvolves administering to that patient a detectably labeled compound asdescribed herein, and detecting the binding of that compound to selectedNNR subtypes (e.g., α7 receptor subtype). Those skilled in the art ofusing diagnostic tools, such as PET and SPECT, can use the radiolabeledcompounds described herein to diagnose a wide variety of conditions anddisorders, including conditions and disorders associated withdysfunction of the central and autonomic nervous systems. Such disordersinclude a wide variety of CNS diseases and disorders, includingAlzheimer's disease, Parkinson's disease, and schizophrenia. These andother representative diseases and disorders that can be evaluatedinclude those that are set forth in U.S. Pat. No. 5,952,339 to Bencherifet al., herein incorporated by reference.

In another aspect, the diagnostic compositions can be used in a methodto monitor selective nicotinic receptor subtypes of a subject, such as ahuman patient. The method involves administering a detectably labeledcompound as described herein to that patient and detecting the bindingof that compound to selected nicotinic receptor subtypes namely, the α7receptor subtype.

Receptor Binding

The compounds of this invention can be used as reference ligands inbinding assays for compounds which bind to NNR subtypes, particularlythe α7 receptor subtype. For this purpose the compounds of thisinvention are preferably labeled with a radioactive isotopic moiety suchas ³H, or ¹⁴C.

V. SYNTHETIC EXAMPLES

The following synthetic examples are provided to illustrate the presentinvention and should not be construed as limiting the scope thereof. Inthese examples, all parts and percentages are by weight, unlessotherwise noted. All solutions are aqueous unless otherwise noted.

Example 1 Small Scale Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide(Compound A) and its Enantiomer,(2R,3S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one

Potassium hydroxide (56 g, 0.54 mole) was dissolved in methanol (420mL). 3-Quinuclidinone hydrochloride (75 g, 0.49 mole) was added and themixture was stirred for 30 min at ambient temperature.3-Pyridinecarboxaldehyde (58 g, 0.54 mole) was added and the mixturestirred for 16 h at ambient temperature. The reaction mixture becameyellow during this period, with solids caking on the walls of the flask.The solids were scraped from the walls and the chunks broken up. Withrapid stirring, water (390 mL) was added. When the solids dissolved, themixture was cooled at 4° C. overnight. The crystals were collected byfiltration, washed with water, and air dried to obtain 80 g of yellowsolid. A second crop (8 g) was obtained by concentration of the filtrateto ˜10% of its former volume and cooling at 4° C. overnight. Both cropswere sufficiently pure for further transformation (88 g, 82% yield).

2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one

2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one (20 g, 93mmol) was suspended in methanol (200 mL) and treated with 46 mL of 6 Mhydrochloric acid. 10% Palladium on carbon (1.6 g) was added and themixture was shaken under 25 psi hydrogen for 16 h. The mixture wasfiltered through diatomaceous earth, and the solvent was removed fromthe filtrate by rotary evaporation. This provided crude2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one hydrochloride, asa white gum (20 g), which was subsequently treated with 2 M sodiumhydroxide (50 mL) and chloroform (50 mL) and stirred for an hour. Thechloroform layer was separated, and the aqueous phase was treated with 2M sodium hydroxide (˜5 mL, enough to raise the pH to 10) and saturatedaqueous Sodium chloride (25 mL). This aqueous mixture was extracted withchloroform (3×10 mL), and the combined chloroform extracts were dried(anhydrous magnesium sulfate) and concentrated by rotary evaporation.The residue (18 g) was dissolved in warm ether (320 mL) and cooled to 4°C. The white solid was filtered off, washed with a small portion of coldether and air dried. Concentration of the filtrate to ˜10% of its formervolume and cooling at 4° C. produced a second crop. A combined yield 16g (79%) was obtained.

3-Amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane

To a stirred solution of2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (3.00 g, 13.9mmol) in dry methanol (20 mL), under nitrogen, was added a 1 M solutionof zinc chloride in ether (2.78 mL, 2.78 mmol). After stirring atambient temperature for 30 min, this mixture was treated with solidammonium formate (10.4 g, 167 mmol). After stirring another hour atambient temperature, solid sodium cyanoborohydride (1.75 g, 27.8 mmol)was added in portions. The reaction was then stirred at ambienttemperature overnight and terminated by addition of water (˜5 mL). Thequenched reaction was partitioned between 5 M sodium hydroxide (10 mL)and chloroform (20 mL). The aqueous layer was extracted with chloroform(20 mL), and combined organic layers were dried (sodium sulfate),filtered and concentrated. This left 2.97 g of yellow gum. GCMS analysisindicated that the product was a 1:9 mixture of the cis and transamines, along with a trace of the corresponding alcohol (98% total massrecovery).

(2R,3S) and(2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane

Di-p-toluoyl-D-tartaric acid (5.33 g, 13.8 mmol) was added to a stirredsolution of crude3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (6.00 g, 27.6mmol of 1:9 cis/trans) in methanol (20 mL). After complete dissolution,the clear solution was then concentrated to a solid mass by rotaryevaporation. The solid was dissolved in a minimum amount of boilingmethanol (˜5 mL). The solution was cooled slowly, first to ambienttemperature (1 h), then for ˜4 h at 5° C. and finally at −5° C.overnight. The precipitated salt was collected by suction filtration andrecrystallized from 5 mL of methanol. Air drying left 1.4 g of whitesolid, which was partitioned between chloroform (5 mL) and 2 M sodiumhydroxide (5 mL). The chloroform layer and a 5 mL chloroform extract ofthe aqueous layer were combined, dried (anhydrous sodium sulfate) andconcentrated to give a colorless oil (0.434 g). The enantiomeric purityof this free base was determined by conversion of a portion into itsN-(tert-butoxycarbonyl)-L-prolinamide, which was then analyzed fordiastereomeric purity (98%) using LCMS.

The mother liquor from the initial crystallization was made basic (˜pH11) with 2 M sodium hydroxide and extracted twice with chloroform (10mL). The chloroform extracts were dried (anhydrous sodium sulfate) andconcentrated to give an oil. This amine (3.00 g, 13.8 mmol) wasdissolved in methanol (10 mL) and treated with di-p-toluoyl-L-tartaricacid (2.76 g, 6.90 mmol). The mixture was warmed to aid dissolution andthen cooled slowly to −5° C., where it remained overnight. Theprecipitate was collected by suction filtration, recrystallized frommethanol and dried. This left 1.05 g of white solid. The salt wasconverted into the free base (yield=0.364 g), and the enantiomericpurity (97%) was assessed using the prolinamide method, as describedabove for the other enantiomer.

Trans Enantiomer A ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide

Diphenylchlorophosphate (0.35 mL, 0.46 g, 1.7 mmol) was added drop-wiseto a solution of benzofuran-2-carboxylic acid (0.28 g, 1.7 mmol) andtriethylamine (0.24 mL, 0.17 g, 1.7 mmol) in dry dichloromethane (5 mL).After stirring at ambient temperature for 30 min, a solution of(2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.337g, 1.55 mmol) (that derived from the di-p-toluoyl-D-tartaric acid salt)and triethylamine (0.24 mL, 0.17 g, 1.7 mmol) in dry dichloromethane (5mL) was added. The reaction mixture was stirred overnight at ambienttemperature, and then treated with 10% sodium hydroxide (1 mL). Thebiphasic mixture was separated, and the organic layer was concentratedon a Genevac centrifugal evaporator. The residue was dissolved inmethanol (6 mL) and purified by HPLC on a C18 silica gel column, usingan acetonitrile/water gradient, containing 0.05% trifluoroacetic acid,as eluent. Concentration of selected fractions, partitioning of theresulting residue between chloroform and saturated aqueous sodiumbicarbonate, and evaporation of the chloroform gave 0.310 g (42% yield)of white powder (95% pure by GCMS). ¹H NMR (300 MHz, CDCl₃) δ 8.51 (d,1H), 8.34 (dd, 1H), 7.66 (d, 1H), 7.58 (dt, 1H), 7.49 (d, 1H), 7.44 (s,1H), 7.40 (dd, 1H), 7.29 (t, 1H), 7.13 (dd, 1H), 6.63 (d, 1H), 3.95 (t,1H), 3.08 (m, 1H), 2.95 (m, 4H), 2.78 (m, 2H), 2.03 (m, 1H), 1.72 (m,3H), 1.52 (m, 1H).

This material (trans enantiomer A) was later determined to be identical,by chiral chromatographic analysis, to material whose absoluteconfiguration is 2S,3R (established by x-ray crystallographic analysis).

Trans Enantiomer B ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide

Diphenylchlorophosphate (96 μL, 124 mg, 0.46 mmol) was added drop-wiseto a solution of the benzofuran-2-carboxylic acid (75 mg, 0.46 mmol) andtriethylamine (64 μL, 46 mg, 0.46 mmol) in dry dichloromethane (1 mL).After stirring at ambient temperature for 45 min, a solution of(2R,3S)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (0.10g, 0.46 mmol) (that derived from the di-p-toluoyl-L-tartaric acid salt)and triethylamine (64 μL, 46 mg, 0.46 mmol) in dry dichloromethane (1mL) was added. The reaction mixture was stirred overnight at ambienttemperature, and then treated with 10% sodium hydroxide (1 mL). Thebiphasic mixture was separated, and the organic layer and a chloroformextract (2 mL) of the aqueous layer was concentrated by rotaryevaporation. The residue was dissolved in methanol and purified by HPLCon a C18 silica gel column, using an acetonitrile/water gradient,containing 0.05% trifluoroacetic acid, as eluent. Concentration ofselected fractions, partitioning of the resulting residue betweenchloroform and saturated aqueous sodium bicarbonate, and evaporation ofthe chloroform gave 82.5 mg (50% yield) of a white powder. The NMRspectrum was identical to that obtained for the 2S,3R isomer.

Since the immediate precursor of this material (trans enantiomer B) isenantiomeric to the immediate precursor of 2S,3R compound (transenantiomer A), the absolute configuration of trans enantiomer B ispresumed to be 2R,3S.

Example 2 Large Scale Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamideand(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)-1-benzofuran-2-carboxamidep-toluenesulfonate salt2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one

3-Quinuclidinone hydrochloride (8.25 kg, 51.0 mol) and methanol (49.5 L)were added to a 100 L glass reaction flask, under an nitrogenatmosphere, equipped with a mechanical stirrer, temperature probe, andcondenser. Potassium hydroxide (5.55 kg, 99.0 mol) was added via apowder funnel over an approximately 30 min period, resulting in a risein reaction temperature from 50° C. to 56° C. Over an approximately 2 hperiod, 3-pyridinecarboxaldehyde (4.80 kg, 44.9 mol) was added to thereaction mixture. The resulting mixture was stirred at 20° C.±5° C. fora minimum of 12 h, as the reaction was monitored by thin layerchromatography (TLC). Upon completion of the reaction, the reactionmixture was filtered through a sintered glass funnel and the filter cakewas washed with methanol (74.2 L). The filtrate was concentrated,transferred to a reaction flask, and water (66.0 L) was added. Thesuspension was stirred for a minimum of 30 min, filtered, and the filtercake was washed with water (90.0 L) until the pH of the rinse was 7-9.The solid was dried under vacuum at 50° C.±5° C. for a minimum of 12 hto give 8.58 kg (89.3%) of2-((3-pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one.

(2S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-onedi-p-toluoyl-D-tartrate salt

2-((3-Pyridinyl)methylene)-1-azabicyclo[2.2.2]octan-3-one (5.40 kg, 25.2mol) and methanol (40.5 L) were added to a 72 L reaction vessel under aninert atmosphere equipped with a mechanical stirrer, temperature probe,low-pressure gas regulator system, and pressure gauge. The headspace wasfilled with nitrogen, and the mixture was stirred to obtain a clearyellow solution. To the flask was added 10% palladium on carbon (50%wet) (270 g). The atmosphere of the reactor was evacuated using a vacuumpump, and the headspace was replaced with hydrogen to 10 to 20 incheswater pressure. The evacuation and pressurization with hydrogen wererepeated 2 more times, leaving the reactor under 20 inches waterpressure of hydrogen gas after the third pressurization. The reactionmixture was stirred at 20° C.±5° C. for a minimum of 12 h, and thereaction was monitored via TLC. Upon completion of the reaction, thesuspension was filtered through a bed of Celite®545 (1.9 kg) on asintered glass funnel, and the filter cake was washed with methanol(10.1 L). The filtrate was concentrated to obtain a semi-solid which wastransferred, under an nitrogen atmosphere, to a 200 L reaction flaskfitted with a mechanical stirrer, condenser, and temperature probe. Thesemi-solid was dissolved in ethanol (57.2 L), anddi-p-toluoyl-D-tartaric acid (DTTA) (9.74 kg, 25.2 mol) was added. Thestirring reaction mixture was heated at reflux for a minimum of 1 h, andfor an additional minimum of 12 h while the reaction was cooled tobetween 15° C. and 30° C. The suspension was filtered using a tabletopfilter, and the filter cake was washed with ethanol (11.4 L). Theproduct was dried under vacuum at ambient temperature to obtain 11.6 kg(76.2% yield, 59.5% factored for purity) of(2S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-onedi-p-toluoyl-D-tartrate salt.

(2S,3R)-3-Amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanedi-n-toluoyl-D-tartrate salt

Water (46.25 L) and sodium bicarbonate (4.35 kg, 51.8 mol) were added toa 200 L flask. Upon complete dissolution, dichloromethane (69.4 L) wasadded. (2S)-2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-onedi-p-toluoyl-D-tartrate salt (11.56 kg, 19.19 mol) was added, and thereaction mixture was stirred for between 2 min and 10 min. The layerswere allowed to separate for a minimum of 2 min (additional water (20 L)was added when necessary to partition the layers). The organic phase wasremoved and dried over anhydrous sodium sulfate. Dichloromethane (34.7L) was added to the remaining aqueous phase, and the suspension wasstirred for between 2 min and 10 min. The layers were allowed toseparate for between 2 min and 10 min. Again, the organic phase wasremoved and dried over anhydrous sodium sulfate. The extraction of theaqueous phase with dichloromethane (34.7 L) was repeated one more time,as above. Samples of each extraction were submitted for chiral HPLCanalysis. The sodium sulfate was removed by filtration, and thefiltrates were concentrated to obtain(2S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (4.0 kg) asa solid.

The (2S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one (3.8 kg)was transferred to a clean 100 L glass reaction flask, under a nitrogenatmosphere, fitted with a mechanical stirrer and temperature probe.Anhydrous tetrahydrofuran (7.24 L) and (+)-(R)-α-methylbenzylamine (2.55L, 20.1 mol) were added. Titanium(IV) isopropoxide (6.47 L, 21.8 mol)was added to the stirred reaction mixture over a 1 h period. Thereaction was stirred under a nitrogen atmosphere for a minimum of 12 h.Ethanol (36.17 L) was added to the reaction mixture. The reactionmixture was cooled to below −5° C., and sodium borohydride (1.53 kg,40.5 mol) was added in portions, keeping the reaction temperature below15° C. (this addition took several hours). The reaction mixture was thenstirred at 15° C.±10° C. for a minimum of 1 h. The reaction wasmonitored by HPLC, and upon completion of the reaction (as indicated byless than 0.5% of(2S)-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-one remaining),2 M sodium hydroxide (15.99 L) was added and the mixture was stirred fora minimum of 10 min. The reaction mixture was filtered through a bed ofCelite®545 in a tabletop funnel. The filter cake was washed with ethanol(15.23 L), and the filtrate was concentrated to obtain an oil.

The concentrate was transferred to a clean 100 L glass reaction flaskequipped with a mechanical stirrer and temperature probe under an inertatmosphere. Water (1 L) was added, and the mixture was cooled to 0°C.±5° C. 2 M Hydrochloric acid (24 L) was added to the mixture to adjustthe pH of the mixture to pH 1. The mixture was then stirred for aminimum of 10 min, and 2 M sodium hydroxide (24 L) was slowly added toadjust the pH of the mixture to pH 14. The mixture was stirred for aminimum of 10 min, and the aqueous phase was extracted withdichloromethane (3×15.23 L). The organic phases were dried overanhydrous sodium sulfate (2.0 kg), filtered, and concentrated to give(2S,3R)—N-((1R)-phenylethyl)-3-amino-2-((3-pyridinyl)methyl))-1-azabicyclo[2.2.2]octane(4.80 kg, 84.7% yield).

The(2S,3R)—N-((1R)-phenylethyl)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanewas transferred to a 22 L glass flask equipped with a mechanical stirrerand temperature probe under an inert atmosphere. Water (4.8 L) wasadded, and the stirring mixture was cooled to 5° C.±5° C. Concentratedhydrochloric acid (2.97 L) was slowly added to the reaction flask,keeping the temperature of the mixture below 25° C. The resultingsolution was transferred to a 72 L reaction flask containing ethanol (18L), equipped with a mechanical stirrer, temperature probe, and condenserunder an inert atmosphere. To the flask was added 10% palladium oncarbon (50% wet) (311.1 g) and cyclohexene (14.36 L). The reactionmixture was heated at near-reflux for a minimum of 12 h, and thereaction was monitored by TLC. Upon completion of the reaction, thereaction mixture was cooled to below 45° C., and it was filtered througha bed of Celite®545 (1.2 kg) on a sintered glass funnel. The filter cakewas rinsed with ethanol (3 L) and the filtrate was concentrated toobtain an aqueous phase. Water (500 mL) was added to the concentratedfiltrate, and this combined aqueous layer was washed with methyltert-butyl ether (MTBE) (2×4.79 L). 2 M Sodium hydroxide (19.5 L) wasadded to the aqueous phase to adjust the pH of the mixture to pH 14. Themixture was then stirred for a minimum of 10 min. The aqueous phase wasextracted with chloroform (4×11.96 L), and the combined organic phaseswere dried over anhydrous sodium sulfate (2.34 kg). The filtrate wasfiltered and concentrated to obtain(2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (3.49kg, >quantitative yield) as an oil.

The (2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanewas transferred to a clean 100 L reaction flask equipped with amechanical stirrer, condenser, and temperature probe under an inertatmosphere. Ethanol (38.4 L) and di-p-toluoyl-D-tartaric acid (3.58 kg,9.27 mol) were added. The reaction mixture was heated at gentle refluxfor a minimum of 1 h. The reaction mixture was then stirred for aminimum of 12 h while it was cooled to between 15° C. and 30° C. Theresulting suspension was filtered, and the filter cake was washed withethanol (5.76 L). The filter cake was transferred to a clean 100 L glassreaction flask equipped with a mechanical stirrer, temperature probe,and condenser under an inert atmosphere. A 9:1 ethanol/water solution(30.7 L) was added, and the resulting slurry was heated at gentle refluxfor a minimum of 1 h. The reaction mixture was then stirred for aminimum of 12 h while cooling to between 15° C. and 30° C. The mixturewas filtered and the filter cake was washed with ethanol (5.76 L). Theproduct was collected and dried under vacuum at 50° C.±5° C. for aminimum of 12 h to give 5.63 kg (58.1% yield) of(2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanedi-p-toluoyl-D-tartrate salt.

(2S,3R)—N-(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide

(2S,3R)-3-Amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanedi-p-toluoyl-D-tartrate salt (3.64 kg, 5.96 mol) and 10% aqueous sodiumchloride solution (14.4 L, 46.4 mol) were added to a 72 L glass reactionflask equipped with a mechanical stirrer under an inert atmosphere. 5 MSodium hydroxide (5.09 L) was added to the stirring mixture to adjustthe pH of the mixture to pH 14. The mixture was then stirred for aminimum of 10 min. The aqueous solution was extracted with chloroform(4×12.0 L), and the combined organic layers were dried over anhydroussodium sulfate (1.72 kg). The combined organic layers were filtered, andthe filtrate was concentrated to obtain(2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octane (1.27kg) as an oil.

The (2S,3R)-3-amino-2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octanewas transferred to a 50 L glass reaction flask equipped with amechanical stirrer under an inert atmosphere. Dichloromethane (16.5 L),triethylamine (847 mL, 6.08 mol), benzofuran-2-carboxylic acid (948 g,5.85 mol) and O-(benzotriazol-1-yl)-N,N,N,1-tetramethyluroniumhexafluorophosphate (HBTU) (2.17 kg, 5.85 mol) were added to thereaction mixture. The mixture was stirred for a minimum of 4 h atambient temperature, and the reaction was monitored by HPLC. Uponcompletion of the reaction, 10% aqueous potassium carbonate (12.7 L,17.1 mol) was added to the reaction mixture and the mixture was stirredfor a minimum of 5 min. The layers were separated and the organic phasewas washed with 10% brine (12.7 L). The layers were separated and theorganic phase was cooled to 15° C.±10° C. 3 M Hydrochloric acid (8.0 L)was slowly added to the reaction mixture to adjust the pH of the mixtureto pH 1. The mixture was then stirred for a minimum of 5 min, and thelayers were allowed to partition for a minimum of 5 min. The solids werefiltered using a table top filter. The layers of the filtrate wereseparated, and the aqueous phase and the solids from the funnel weretransferred to the reaction flask. 3 M Sodium hydroxide (9.0 L) wasslowly added to the flask in portions to adjust the pH of the mixture topH 14. The aqueous phase was extracted with dichloromethane (2×16.5 L).The combined organic phases were dried over anhydrous sodium sulfate(1.71 kg). The mixture was filtered, and the filtrate was concentratedto give(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide(1.63 kg, 77.0% yield) as a yellow solid.

(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl]benzofuran-2-carboxamidep-toluenesulfonate

(2S,3R)—N-(2-((3-Pyridinyl)methyl)-1-azabicyclo[2.2.2]octan-3-yl)benzofuran-2-carboxamide(1.62 kg, 4.48 mol) and dichloromethane (8.60 kg) were added into acarboy. The weight/weight percent of the material in solution wasdetermined through HPLC analysis. The solution was concentrated to anoil, acetone (4 L) was added, and the mixture was concentrated to anoily solid. Additional acetone (12 L) was added to the oily solid in therotary evaporator bulb, and the resulting slurry was transferred to a 50L glass reaction flask with a mechanical stirrer, condenser, temperatureprobe, and condenser under an inert atmosphere. The reaction mixture washeated to 50° C.±5° C. Water (80.7 g) was added to the solution, and itwas stirred for a minimum of 10 min. p-Toluenesulfonic acid (853 g, 4.44mol) was added to the reaction mixture in portions over approximately 15min. The reaction mixture was heated to reflux and held at thattemperature for a minimum of 30 min to obtain a solution. The reactionwas cooled to 40° C.±5° C. over approximately 2 h. Isopropyl acetate(14.1 L) was added over approximately 1.5 h. The reaction mixture wasslowly cooled to ambient temperature over a minimum of 10 h. The mixturewas filtered and the filter cake was washed with isopropyl acetate (3.5L). The isolated product was dried under vacuum at 105° C.±5° C. forbetween 2 h and 9 h to give 2.19 kg (88.5% yield) of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidep-toluenesulfonate, mp 226-228° C. ¹H NMR (500 MHz, D₂O) δ 8.29 (s, 1H),7.78 (m, J=5.1, 1H), 7.63 (d, J=7.9, 1H), 7.54 (d, J=7.8, 1H), 7.49 (d,J=8.1, 2H), 7.37 (m, J=8.3, 1H), 7.33 (m, J=8.3, 6.9, 1.0, 1H), 7.18 (m,J=7.8, 6.9, 1.0, 1H), 7.14 (d, J=8.1, 2H), 7.09 (s, 1H), 6.99 (dd,J=7.9, 5.1, 1H), 4.05 (m, J=7.7, 1H), 3.74 (m, 1H), 3.47 (m, 2H), 3.28(m, 1H), 3.22 (m, 1H), 3.15 (dd, J=13.2, 4.7, 1H), 3.02 (dd, J=13.2,11.5, 1H), 2.19 (s, 3H), 2.02 (m, 2H), 1.93 (m, 2H), 1.79 (m, 1H). ¹³CNMR (126 MHz, D₂O) δ 157.2, 154.1, 150.1, 148.2, 146.4, 145.2, 138.0,137.0, 130.9, 128.2 (2), 126.9, 126.8, 125.5 (2), 123.7, 123.3, 122.7,111.7, 100.7, 61.3, 50.2, 48.0, 40.9, 33.1, 26.9, 21.5, 20.8, 17.0.

Samples of this material were converted into Compound A free base (foruse in salt selection studies) by treatment with aqueous sodiumhydroxide and extraction with chloroform. Thorough evaporation of thechloroform left an off-white powder, mp 167-170° C., with the followingspectral characteristics: Positive ion electrospray MS [M+H]⁺ ionm/z=362. ¹H NMR (500 MHz, DMSO-d₆) δ 8.53 (d, J=7.6 Hz, 1H), 8.43 (d,J=1.7 Hz, 1H), 8.28 (dd, J=1.6, 4.7 Hz, 1H), 7.77 (d, J=7.7 Hz, 1H),7.66 (d, J=8.5 Hz, 1H), 7.63 (dt, J=1.7, 7.7 Hz, 1H), 7.52 (s, 1H), 7.46(m, J=8.5, 7.5 Hz, 1H), 7.33 (m, J=7.7, 7.5 Hz, 1H), 7.21 (dd, J=4.7,7.7 Hz, 1H), 3.71 (m, J=7.6 Hz, 1H), 3.11 (m, 1H), 3.02 (m, 1H), 2.80(m, 2H), 2.69 (m, 2H), 2.55 (m, 1H), 1.80 (m, 1H), 1.77 (m, 1H), 1.62(m, 1H), 1.56 (m, 1H), 1.26 (m, 1H). ¹³C NMR (126 MHz, DMSO-d₆) δ 158.1,154.1, 150.1, 149.1, 146.8, 136.4, 135.4, 127.1, 126.7, 123.6, 122.9,122.6, 111.8, 109.3, 61.9, 53.4, 49.9, 40.3, 35.0, 28.1, 26.1, 19.6.

The monohydrochloride salt of Compound A (see Example 5) was submittedfor x-ray crystallographic analysis. The resulting crystal structure(shown in FIGS. 10A and 10B, respectively) established the 2S,3Rabsolute configuration of Compound A.

Example 3 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidephosphate salt

To a round bottom flask was added(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(8.18 g, 22.6 mmol) and 2-propanol (180 mL). The mixture was stirred andheated at 65-70° C. until all solids had dissolved. The solution wasvigorously stirred at 65-70° C., and phosphoric acid (1.65 mL, 24.3mmol) was added drop-wise by pipette. Immediately, a white, granularsolid formed. The mixture was stirred at 65-70° C. for 30 minutes,cooled to ambient temperature (23° C.) and stirred for an additional 24h. The white solids were collected by suction filtration, the filtercake was washed with 2-propanol (20 mL) and the solid was air-dried forat least 1 h. The solid was dried further in a vacuum oven at 75° C.overnight (16 h) to give 10.7 g of the product (>quantitative yield), mp265-273° C. with decomposition, with crystallinity changes observed at˜180° C. ¹H-NMR (DMSO-d₆) indicated the presence of 2-propanol (strongsolvate), which may explain the greater than quantitative yield. ChiralLC analysis gave a purity of 97.1% (270 nm).

Example 4 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemaleate salt

Maleic acid (0.067 g, 0.630 mmol) was added to a hot slurry of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(0.203 g, 0.560 mmol) in isopropyl acetate (2 mL), depositing fine,white solids, along with a gummy residue. Additional isopropyl acetate(3 mL) and maleic acid (0.006 g) were added, and the mixture was heatedto reflux. Isopropanol (5 mL) was added at reflux. The resulting mixtureof white solids was cooled to ambient temperature, filtered, and thesolids were washed with isopropyl acetate (2 mL). The product was driedunder vacuum at 60° C. for 18 h to give 0.228 g of an off-white, flakysolid (84.7% yield), mp 180-182° C. ¹H NMR (DMSO-d₆) indicated amono-salt stoichiometry. Calc'd for C₂₂H₂₃N₃O₂.C₄H₄O₄: C, 65.40; H,5.70; N, 8.80; Found: C, 65.35, 65.29; H, 5.86, 5.68; N, 8.69, 8.78.

Example 5 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehydrochloride salts

Monohydrochloride: A hydrochloric acid/THF solution was prepared byadding of concentrated hydrochloric acid (1.93 mL of 12M, 23.2 mmol)drop-wise to 8.5 mL of chilled THF. The solution was warmed to ambienttemperature. To a round bottom flask was added(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(8.49 g, 23.5 mmol) and acetone (85 mL). The mixture was stirred andheated at 45-50° C. until a complete solution was obtained. Thehydrochloric acid/THF solution prepared above was added drop-wise over a5 min period, with additional THF (1.5 mL) used in the transfer.Granular, white solids began to form during the addition of the acidsolution. The mixture was cooled to ambient temperature, and stirredovernight (16 h). The solids were collected by suction filtration, thefilter cake was washed with acetone (10 mL), and the solid was air-driedwith suction for 30 min. The solid was further dried in a vacuum oven at75° C. for 2 h to give 8.79 g of the fine white crystals (94% yield), mp255-262° C. Chiral LC analysis gave a purity of 98.8% (270 nm). ¹H-NMR(DMSO-d₆) shows no residual solvents and confirms mono stoichiometry. ¹HNMR (300 MHz, DMSO-d₆) δ 10.7 (broad s, 1H—quaternary ammonium), 8.80(broad s, 1H—amide H), 8.54 (s, 1H), 8.23 (d, 1H), 7.78 (d, 1H), 7.74(d, 1H), 7.60 (d, 1H), 7.47 (m, 2H), 7.33 (m, 1H), 7.19 (m, 1H), 4.19(m, 1H), 4.08 (m, 1H), 3.05-3.55 (m, 6H), 2.00-2.10 (m, 3H), 1.90 (m,1H), 1.70 (m, 1H). An x-ray crystallographic analysis of this saltestablished stereochemical assignment and stoichiometry (see FIGS. 10Aand 10B).

Dihydrochloride: Hydrogen chloride gas was slowly bubbled into a icecooled solution of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(1.9 g, 5.3 mmol) in anhydrous ether (25 mL). The volatiles wereremoved, first in a nitrogen stream and then with high vacuum (sodiumhydroxide scrubber in high vacuum line). The residue was trituratedseveral times with small volumes of anhydrous ether (discarded), and theremaining solid was dried under high vacuum. This gave 2.17 g (94%yield) of off-white powder, mp 210-212° C. (hygroscopic). Chiral LCanalysis gave a purity of 93.7% (270 nm). Positive ion electrospray MS[M+H]⁺ ion m/z=362. ¹H NMR (300 MHz, CD₃OD) δ 9.15 (s, 1H), 8.84 (d,1H), 8.63 (d, 1H), 7.97 (t, 1H), 7.75 (d, 1H), 7.61 (d, 1H), 7.52 (m,2H), 7.35 (t, 1H), 4.50 (m, 1H), 4.32 (m, 1H), 3.40-3.85 (m, 6H),1.95-2.40 (m, 5H).

Example 6 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehemigalactarate salt

Galactaric (mucic) acid (36.3 mg, 0.173 mmol) was added to a solution of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). The mixture was refluxed aswater (8 drops) was added; then the hot mixture was filtered through acotton plug, which was subsequently rinsed with ethanol (1 mL). Coolingfailed to give a precipitate. The volatiles were removed by rotaryevaporation, and the residue (white foam) was triturated withisopropanol (discarded), and the remaining solid dissolved in refluxingacetone/water (4 mL of 7:1). Slow cooling to 5° C. produced a whitesolid, which was filtered off, washed with isopropanol (3×1 mL), anddried under high vacuum. This left 118 mg (73% yield) fine white plates,mp 134-139° C. ¹H NMR (300 MHz, D₂O) δ 8.29 (s, 1H), 7.78 (d, 1H), 7.62(d, 1H), 7.54 (d, 1H), 7.35 (m, 2H), 7.18 (t, 1H), 7.10 (s, 1H), 6.98(m, 1H), 4.08 (s, 1H, galactaric acid), 3.98 (d, 1H), 3.77 (s, 1H,galactaric acid), 3.66 (m, 1H), 3.35 (m, 1H), 2.95-3.30 (m, 4H),1.65-2.05 (m, 5H).

Example 7 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideD-tartrate salt

Tartaric acid (25.6 mg, 0.173 mmol) was added to a solution of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). The resulting solution wasslowly cooled to ambient temperature. No solids precipitated, so thesolution was concentrated to give a white foam. Attempts to crystallizein isopropanol failed. The foam was dissolved in methanol and anotherhalf-equivalent of tartaric acid (25.6 mg, 0.173 mmol) was added. Themixture was concentrated to give a white foam, which would notcrystallize from mixtures of methanol and isopropanol. The concentratedmaterial (mixture of solid and gummy liquid) was then slurried in ethylacetate (1 mL), producing a white solid. This was isolated by filtration(ethyl acetate wash) and drying in a vacuum oven (18 h at 40° C.), togive 141 mg (79.7% yield) of the mono stoichiometry salt (NMR), mp136-140° C. Chiral LC analysis gave a purity of 98.1% (270 nm). ¹H NMR(300 MHz, D₂O) δ 8.50 (s, 1H), 8.01 (d, 1H), 7.86 (d, 1H), 7.75 (d, 1H),7.56 (m, 2H), 7.38 (t, 1H), 7.32 (s, 1H), 7.21 (t, 1H), 4.34 (s, 2H,tartaric acid), 4.26 (d, 1H), 3.95 (m, 1H), 3.64 (m, 2H), 3.15-3.55 (m,4H), 1.90-2.30 (m, 5H).

Example 8 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemethanesulfonate salt

Methanesulfonic acid (33.2 mg, 0.346 mmol) was added to a solution of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). Cooling failed to produce aprecipitate. The mixture was refluxed, and the hot mixture was filteredthrough a cotton plug, which was subsequently rinsed with methanol (1mL). The volatiles were removed by rotary evaporation, and the residue(light yellow foam) was dissolved in hot isopropanol (1 mL). Again,cooling failed to give a precipitate. The isopropanol was evaporated,and the residue was slurried in acetone (1 mL). Filtration and vacuumoven drying (18 h at 50° C.) gave 146 mg (92.5% yield) of light beigesolid, mp 240-243° C. ¹H NMR (300 MHz, D₂O) δ 8.32 (s, 1H), 7.82 (d,1H), 7.66 (d, 1H), 7.57 (d, 1H), 7.38 (m, 2H), 7.20 (m, 1H), 7.12 (s,1H), 7.01 (m, 1H), 4.09 (d, 1H), 3.75 (m, 1H), 3.47 (m, 2H), 3.00-3.40(m, 4H), 2.67 (s, 3H, methanesulfonic acid), 1.75-2.15 (m, 5H).

Example 9 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideD-mandelate salt

D-Mandelic acid (52.6 mg, 0.346 mmol) was added to a solution of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). Dilution with ethyl acetate(4 mL) and cooling failed to produce a precipitate. The volatiles wereremoved by rotary evaporation, and the residue (white foam) wasdissolved in hot isopropanol (0.5 mL). Cooling to 5° C. produced whitecrystals which were collected by suction filtration. Vacuum oven drying(18 h at 45° C.) gave 111 mg (62.4% yield) of light beige solid, mp188.5-193° C. ¹H NMR (300 MHz, D₂O) δ 8.33 (s, 1H), 7.83 (s, 1H), 7.67(d, 1H), 7.60 (d, 1H), 7.27 (m, 8H, includes mandelic acid), 7.12 (s,1H), 7.01 (m, 1H), 4.85 (s, 1H, mandelic acid), 4.10 (d, 1H), 3.75 (m,1H), 3.48 (m, 2H), 3.00-3.40 (m, 4H), 1.75-2.15 (m, 5H).

Example 10 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideR-camphorsulfonate salt

R-10-Camphorsulfonic acid (80.3 mg, 0.346 mmol) was added to a solutionof(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). Cooling failed to depositany precipitate. The volatiles were removed by rotary evaporation, andthe residue (white foam) was dissolved in hot isopropanol (0.5 mL).Cooling to 5° C. produced a few white crystals and a milky suspension.Scratching the sides of the flask with a spatula eventually transformedthe mixture into a thick mass of fine white crystals. Another 0.5 mL ofisopropanol was added, and the crystals were collected by suctionfiltration. Vacuum oven drying (5 h at 70° C., followed by 2 h at 110°C.) gave 193 mg (93.8% yield) of white solid, mp 149.5-156° C. ¹H NMR(300 MHz, D₂O) 8.30 (s, 1H), 7.79 (d, 1H), 7.64 (d, 1H), 7.55 (d, 1H),7.36 (m, 2H), 7.18 (m, 1H), 7.11 (s, 1H), 6.99 (m, 1H), 4.07 (d, 1H),3.73 (m, 1H), 3.45 (m, 2H), 3.95-3.35 (m, 5H, includes camphorsulfonicacid), 2.64 (d, 1H, camphorsulfonic acid), 2.22 (m, 2H), 1.70-2.10 (m,8H, includes camphorsulfonic acid), 1.45 (m, 1H, camphorsulfonic acid),1.25 (m, 1H, camphorsulfonic acid), 0.85 (s, 3H, camphorsulfonic acid),0.68 (s, 3H, camphorsulfonic acid).

Example 11 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideS-camphorsulfonate salt

S-10-Camphorsulfonic acid (80.3 mg, 0.346 mmol) was added to a solutionof(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide(125 mg, 0.346 mmol) in hot ethanol (1 mL). Dilution with ethyl acetate(4 mL) and cooling failed to deposit any precipitate. The volatiles wereremoved by rotary evaporation, and the residue (white foam) wasdissolved in hot isopropanol (1.5 mL). Cooling to 5° C. produced whitecrystals. The mixture was concentrated to ˜0.5 mL and cooled again to 5°C. The solid was then collected by suction filtration and vacuum dried,initially 18 h at 45° C., but then at successively higher temperatures(finally at 110° C.) to remove residual isopropanol. This provided 143mg (69.7% yield) of white solid, mp 153.5-157° C. ¹H NMR (300 MHz, D₂O)δ 8.29 (s, 1H), 7.79 (d, 1H), 7.63 (d, 1H), 7.54 (d, 1H), 7.34 (m, 2H),7.18 (m, 1H), 7.10 (s, 1H), 6.99 (m, 1H), 4.05 (d, 1H), 3.73 (m, 1H),3.44 (m, 2H), 3.95-3.35 (m, 5H, includes camphorsulfonic acid), 2.67 (d,1H, camphorsulfonic acid), 2.23 (m, 2H), 1.70-2.10 (m, 8H, includescamphorsulfonic acid), 1.46 (m, 1H, camphorsulfonic acid), 1.25 (m, 1H,camphorsulfonic acid), 0.84 (s, 3H, camphorsulfonic acid), 0.64 (s, 3H,camphorsulfonic acid).

Using procedures similar to those reported above (examples 3-11),several other salt forms were characterized. The results of thesepreparations are reported in examples 12-14.

Example 12 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidesulfate salt

A sulfate salt was precipitated from a mixture of isopropyl acetate andwater. MP 278° C. ¹H NMR (400 MHz, DMSO-d₆) δ9.28 (broad s, 1H, amide),8.56 (dd, 1H), 8.24 (t, 1H), 7.77 (d, 1H), 7.74 (d, 1H), 7.60 (s, 1H),7.40 (m, 2H), 7.35 (s, 1H), 7.21 (m, 1H), 4.21 (m, 1H), 3.93 (m, 2H),3.10-3.60 (m, 5H), 2.05 (m, 3H), 1.92 (m, 1H), 1.73 (m, 1H).

Example 13 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideketoglutarate salt

An α-ketoglutarate salt was precipitated from isopropyl acetate. MP 177°C. ¹H NMR (400 MHz, DMSO-d₆) δ8.64 (s, 1H, amide), 8.50 (d, 1H), 8.20(d, 1H), 7.74 (d, 1H), 7.70 (d, 1H), 7.60 (m, 1H), 7.45 (m, 1H), 7.32(m, 2H), 7.18 (m, 1H), 4.10 (m, 1H), 3.78 (m, 2H), 3.00-3.45 (m, 5H),2.81 (m, 2H, ketoglutaric acid), 2.41 (m, 2H, ketoglutaric acid), 1.96(m, 3H), 1.83 (m, 1H), 1.60 (m, 1H).

Example 14 Synthesis of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehippurate salt

A hippurate salt was precipitated from acetone (too hygroscopic toobtain melting point). ¹H NMR (400 MHz, DMSO-d₆) δ 8.79 (s, 1H, amide),8.56 (d, 1H), 8.44 (s, 1H, hippuric acid), 8.29 (m, 1H), 7.87 (m, 2H,hippuric acid), 7.76 (d, 1H), 7.65 (m, 1H), 7.54 (m, 1H), 7.49 (m, 4H,includes hippuric acid), 7.34 (m, 2H), 7.21 (m, 1H), 3.91 (m, 1H), 3.74(m, 2H), 3.00-3.50 (m, 5H), 2.80 (m, 2H, hippuric acid), 1.79 (m, 2H),1.60 (m, 2H), 1.30 (m, 1H).

Example 15 Isolation of (2R,3R)— and(2S,3S)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideand Conversion to galactaric acid salts

A sample of the supernatant from the isolation of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl]benzofuran-2-carboxamidep-toluenesulfonate (Example 2) was concentrated by rotary evaporation,adjusted pH 10 with 10% aqueous sodium hydroxide and extracted withdichloromethane. The dichloromethane extract was evaporated, and theresidue (1.8 g) was dissolved in absolute ethanol (55 mL) containing0.5% di-n-butylamine. This solution was injected, in 0.25 mL portions,onto a 25 cm×2.1 cm Chiralpak® AD chiral HPLC column, eluting with60:40:0.2 hexane/ethanol/di-n-butylamine (flow rate=30 mL/min),monitored at 270 nm. Isolation of the effluent eluting at ˜7.5 min andthat eluting at ˜13.5 min gave, after evaporation of the solvent, 0.48 g(98% chiral purity) and 0.47 g (99% chiral purity) respectively ofcolorless oil. The two NMR spectra were identical. ¹H NMR (300 MHz,CDCl₃) δ 8.49 (s, 1H), 8.45 (d, 1H), 7.74 (d, 1H), 7.52 (m, 4H), 7.35(t, 1H), 7.20 (dd, 1H), 7.05 (d, 1H), 4.55 (dt, 1H), 3.43 (m, 1H), 3.22(m, 1H), 2.90 (m, 5H), 2.09 (m, 1H), 1.88 (m, 4H).

A warm solution of each free base samples in absolute ethanol (10 mL)was treated with one equivalent of galactaric acid. The resultingmixtures were heated at 75° C. for 5 min and cooled, with stirring, toambient temperature. The resulting solids were collected by suctionfiltration and vacuum dried, giving 0.65 g (87% yield) and 0.62 g (85%yield) respectively of white granular solid (mp 200-205° C. in eachcase). ¹H NMR (300 MHz, D₂O) δ 8.38 (s, 1H), 8.28 (d, 1H), 7.94 (d, 1H),7.70 (d, 1H), 7.59 (d, 1H), 7.48 (t, 1H), 7.40 (m, 1H), 7.32 (m, 2H),4.42 (m, 1H), 4.21 (s, 2H), 3.87 (s, 2H), 3.68 (m, 1H), 3.35 (m, 6H),2.25 (m, 2H), 2.02 (m, 3H).

Example 16 Synthesis of(2R,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidep-chlorobenzoate salt

Solid p-chlorobenzoic acid (46.8 mg, 0.299 mmol) was added in oneportion to a solution of the earlier eluting isomer ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl]benzofuran-2-carboxamidefrom Example 15 (108 mg, 0.299 mmol) in acetone (10 mL). This mixturewas warmed to near reflux for 30 min and cooled to ambient temperature.No precipitate formed, so the solution was concentrated to about 20% ofits former volume (hot plate), at which point crystals began to form.The mixture was cooled and diluted with isopropanol (2 mL). This mixturewas concentrated by slow evaporation of solvent at ambient temperature,and the resulting solids were collected and dried. This produced 145 mg(94% yield) of light yellow crystals, mp 150-152° C. ¹H NMR (300 MHz,CDCl₃) δ 8.49 (s, 1H), 8.38 (d, 1H), 7.93 (d, 2H, p-chlorobenzoic acid),7.67 (m, 2H), 7.57 (d, 1H), 7.45 (m, 1H), 7.36 (d, 2H, p-chlorobenzoicacid), 7.30 (m, 1H), 7.27 (s, 1H), 7.16 (m, 1H), 7.00 (d, 1H, amide),6.90 (broad s, quaternary ammonium), 4.62 (m, 1H), 3.85 (dd, 1H), 3.36(m, 1H), 2.95-3.25 (m, 5H), 2.16 (s, 1H), 1.70-2.10 (m, 4H).

X-ray crystallographic analysis of this sample revealed its absolutestereochemistry to be 2R,3R (see FIGS. 11A and 11B). The later elutingisomer in Example 15 thus by elimination, has 2S,3S absoluteconfiguration.

Example 17 Chiral Chromatographic Method for Analysis of theStereoisomers

Generation of a chiral chromatographic method for separation of the fourstereoisomers, one from another, proved very challenging. The initialattempts (using hexane/isopropanol/triethylamine mobile phase) resultedin overlapping peaks and less than optimal peak shapes. Switching fromisopropanol to ethanol and from triethylamine to di-n-butylamineimproved resolution and peak shape and shortened the run time. Thedetails of the method are as follows:

Analytical Column: Chiralpak® AD (250×4.6 mm, 5 μm)

Mobile Phase: 60:40:0.2 hexanes/ethanol/di-n-butylamine

Injection Volume: 10 μL

Flow Rate: 1.0 mL per minute

Temperature: 20° C. Detection: UV at 270 nm

Total Run Time: ˜25 minutesElution Order (RT): 2S,3R (5.3 min); 2R,3S (7.3 min); 2R,3R (8.3 min);2S,3S (12.1 min) A representative chromatogram of the stereoisomeranalogues is shown in FIG. 12.

Example 18 XRPD

XRPD analysis was performed for several salt samples herein described.Diffraction patterns for the hydrochloride (FIG. 13) and the tosylate(FIG. 14) salts are provided.

X-Ray Powder Diffraction (XRPD)

X-Ray Powder Diffraction patterns were collected either or both of twoinstruments. Some were collected on a Siemens D5000 diffractometer usingCuKα radiation (40 kV, 40 mA), θ-θ goniometer, V20 divergence andreceiving slits, a graphite secondary monochromator and a scintillationcounter. The instrument was performance checked using a certifiedCorundum standard (NIST 1976). Samples run under ambient conditions wereprepared as flat plate specimens using powder as received. Approximately35 mg of the sample was gently packed into a cavity cut into polished,zero-background (510) silicon wafer. The sample was rotated in its ownplane during analysis, scanning from 2° to 42° in steps of 0.05° at 4seconds per step, using CuKα1 (λ=1.5406 Å).

Some X-Ray Powder Diffraction patterns were collected on a Bruker AXS C2GADDS diffractometer using CuKα radiation (40 kV, 40 mA), automated XYZstage, laser video microscope for auto-sample positioning and a HiStar2-dimensional area detector. X-ray optics consists of a single Göbelmultilayer mirror coupled with a pinhole collimator of 0.3 mm. The beamdivergence (i.e. the effective size of the X-ray beam on the sample) wasapproximately 4 mm. A θ-θ continuous scan mode was employed with asample-detector distance of 20 cm which gives an effective 2θ range of3.2°-30.0°. Typically the sample would be exposed to the X-ray beam for120 seconds. Samples run under ambient conditions were prepared as flatplate specimens using powder as received without grinding. Approximately1-2 mg of the sample was lightly pressed on a silicon wafer to obtain aflat surface. Samples run under non-ambient conditions were mounted on asilicon wafer with heat-conducting compound. The sample was then heatedto the appropriate temperature at ca. 10° C./min and subsequently heldisothermally for about 5 min before data collection was initiated.

Differential Scanning Calorimetry (DSC)

DSC data were collected on a TA Instruments Q1000 equipped with a 50position auto-sampler. The instrument was calibrated for energy andtemperature calibration using certified indium. Typically 0.5-1.5 mg ofeach sample, in a pin-holed aluminium pan, was heated at 10° C./min from25° C. to 175-200° C. A nitrogen purge at 30 mL/min was maintained overthe sample.

Thermo-Gravimetric Analysis (TGA)

TGA data were collected on a TA Instruments Q500 TGA, equipped with a 16position auto-sampler. The instrument was temperature calibrated usingcertified Alumel. Typically 5-10 mg of each sample was loaded onto apre-tared platinum crucible and aluminium DSC pan, and was heated at 10°C./min from ambient temperature to 350° C. A nitrogen purge at 60 mL/minwas maintained over the sample.

Polarized Light Microscopy (PLM)

Samples were studied on a Leica LM/DM polarized light microscope with adigital video camera for image capture. A small amount of each samplewas placed on a glass slide, mounted in immersion oil and covered with aglass slip, the individual particles being separated as well aspossible. The sample was viewed with appropriate magnification andpartially polarised light, coupled to a λ false-color filter.

Hot Stage Microscopy (HSM)

Hot Stage Microscopy was carried out using a Leica LM/DM polarized lightmicroscope combined with a Mettler-Toledo MTFP82HT hot-stage and adigital video camera for image capture. A small amount of each samplewas placed onto a glass slide with individual particles separated aswell as possible. The sample was viewed with appropriate magnificationand partially polarized light, coupled to a λ false-color filter, whilstbeing heated from ambient temperature typically at 10° C./min.

Gravimetric Vapor Sorption (GVS)

Sorption isotherms were determined on either or both of two instruments.Some were experiments were run using a VTI Corporation SGA-100 moisturesorption analyzer, controlled by VTI FlowSystem 4 software. The sampletemperature was maintained at 25° C. with the aid of a Polyscienceconstant temperature bath. The humidity was controlled by mixing streamsof dry and wet nitrogen. The weight change as a function of % RH wasmonitored using a Cahn Digital Recording Balance D-200 with an accuracyof +/−0.0001 g.

Typically a 10-20 mg sample was placed on the tared balance pan underambient conditions. The sample was dried at 50° C. for 1 h. The standardadsorption isotherm was performed at 25° C. at 5% RH intervals over a5-95% RH range, and the desorption isotherm was similarly done at 25° C.at 5% RH intervals over a 95-5% RH range. Sample equilibration criteriaincluded 0.0100 wt % in 5 min or a maximum equilibration time of 180 minfor each % RH data point.

Some sorption isotherms were obtained using a Hiden IGASorp moisturesorption analyser, controlled by CFRSorp software. The sampletemperature was maintained at 25° C. by a Huber re-circulating waterbath. The humidity was controlled by mixing streams of dry and wetnitrogen, with a total flow rate of 250 mL/min. The relative humiditywas measured by a calibrated Vaisala RH probe (dynamic range of 0-95%RH), located near the sample. The weight change, (mass relaxation) ofthe sample as a function of % RH was constantly monitored by themicrobalance (accuracy±0.001 mg). Typically 10-20 mg of sample wasplaced in a tared mesh stainless steel basket under ambient conditions.The sample was loaded and unloaded at 40% RH and 25° C. (typical ambientconditions). A moisture sorption isotherm was performed as outlinedbelow (2 scans giving 1 complete cycle). The standard isotherm wasperformed at 25° C. at 10% RH intervals over a 0-90% RH range.

GVS Generic Method Parameters

Parameters Values Adsorption - Scan 1 40-90 Desorption/Adsorption - Scan2 85 - Dry, Dry - 40 Intervals (% RH) 10 Number of Scans 2 Flow rate(mL/min) 250 Temperature (° C.) 25 Stability (° C./min) 0.05 MinimumSorption Time (hours) 1 Maximum Sorption Time (hours) 4 Mode AF2Accuracy (%) 98

The software uses a least squares minimization procedure together with amodel of the mass relaxation, to predict an asymptotic value. Themeasured mass relaxation value must be within 5% of that predicted bythe software, before the next % RH value is selected. The minimumequilibration time was set to 1 h and the maximum to 4 h. Typically,samples were recovered after completion of the isotherm and re-analyzedby XRPD.

Water Determination by Karl Fischer (KF)

The water content of each sample was measured on a Mettler Toledo DL39Coulometer using Hydranal Coulomat AG reagent and an argon purge.Weighed solid samples were introduced into the vessel on a platinum TGApan which was connected to a subaseal to avoid water ingress. Approx 10mg of sample was used per titration and duplicate determination weremade.

Thermodynamic Aqueous Solubility by HPLC

Aqueous solubility was determined by suspending sufficient compound in0.25 mL of water to give a maximum final concentration of ≧10 mg/mL ofthe parent free-form of the compound. The suspension was equilibrated at25° C. for 24 h, and then the pH was measured. The suspension was thenfiltered through a glass fiber C filter into a 96 well plate. Thefiltrate was then diluted by a factor of 101. Quantitation was by HPLCwith reference to a standard solution of approximately 0.1 mg/mL inDMSO. Different volumes of the standard, diluted and undiluted samplesolutions were injected. The solubility was calculated using the peakareas determined by integration of the peak found at the same retentiontime as the principal peak in the standard injection. If there wassufficient solid in the filter plate, the XRPD was collected.

Generic Method Details for Thermodynamic Aqueous Solubility Method

Type of method: Reverse phase with gradient elution Column: PhenomenexLuna, C18 (2) 5 μm, 50 × 4.6 mm Column Temperature 25 (° C.): Injection(μL): 5, 8 and 50 Detection: 260, 80 Wavelength, Bandwidth (nm): FlowRate (mL/min): 2 Phase A: 0.1% TFA in water Phase B: 0.085% TFA inacetonitrile Time (min) % Phase A % Phase B Timetable: 0.0 95 5 1.0 8020 2.3 5 95 3.3 5 95 3.5 95 5 4.4 95 5

Chemical Purity by HPLC

Purity analysis was performed on an Agilent HP1100 series systemequipped with a diode array detector and using ChemStation software v9.One of the two methods detailed below was used.

Method 1

Type of method Reverse phase with gradient elution Column: Kromasil 5 μmC18, 150 × 4.6 mm Column Temperature 26 (° C.): Injection (μL): 10Detection: 302, 8 Wavelength, Bandwidth (nm): Flow Rate (mL/min): 1.0Phase A: 0.0256 M KH2PO4 + 0.02 M 1-hexane sulphonic acid Na salt PhaseB: Acetonitrile Time (min) % Phase A % Phase B Timetable: 0 90 10 8 9010 40 10 90 41 90 10 49 90 10 50 90 10

Method 2

Type of method Reverse phase with gradient elution Column: PhenomenexLuna C18 (2), 150 × 4.6 mm, 5 μm Column Temperature 25 (° C.): Injection(μL): 5 Detection: 255, 90 Wavelength, Bandwidth (nm): Flow Rate(mL/min): 1 Phase A: 0.1% TFA in water Phase B: 0.085% TFA inacetonitrile Time (min) % Phase A % Phase B Timetable: 0 95 5 25 5 9525.2 95 5 30 95 5

Ion Chromatography

Data were collected on a Metrohm 861 Advanced Compact IC using IC Netsoftware v2.3. Samples were prepared as 1000 ppm stocks in water. Wheresample solubility was low, a suitable co-solvent such as DMSO was used.Samples were diluted to 50 ppm or 100 ppm with an appropriate solventprior to testing. Quantification was achieved by comparison withstandard solutions of known concentration of the ion being analyzed.

Ion Chromatography Method for Anions

Type of method Anion exchange Column: Metrosep A Supp 5 - 250 (4.0 × 250mm) Column Temperature Ambient (° C.): Injection (μL): 20 Detection:Conductivity detector Flow Rate (mL/min): 0.7 Eluent: 3.2 mM sodiumcarbonate, 1.0 mM sodium hydrogen carbonate in water

Ion Chromatography Method for Cations

Type of method Cation exchange Column: Metrosep C 2 - 250 (4.0 × 250 mm)Column Temperature (° C.): Ambient Injection (μL): 20 Detection:Conductivity detector Flow Rate (mL/min): 1.0 Eluent; 4.0 mM Tartaricacid, 0.75 mM Dipicolinic acid in water

Approximately 50 mg of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehydrochloride was weighed into a glass vial and heated to 50° C. 100 μlportions of 1-butanmol/water (5 volume % water) were added to the soliduntil a clear solution was formed (500 μl total). The sample was stirredfor 50° C. for 1 hour and observations were made. After heating at 50°C. for an hour the sample remained a clear solution and was cooled from50° C. to 25° C. at a rate of 1.4° C. per hour. The sample remained aclear solution on cooling and was covered with parafilm, pin-holed, andleft to evaporate at ambient temperature. After 2 weeks, large crystalswere seen in the partially evaporated sample. FIG. 13 is an XRPD of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride illustrating both observed (lighter) and calculated(darker) patterns.

The experimental pattern is from the sample of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride while the calculated example is from the singlecrystal X-ray structure as herein described and depicted in FIGS. 10Aand 10B. Both patterns are in agreement in respect of 2Θ values andminor difference in intensities and peak widths may be attributed toinstrument resolution and preferred orientation effects. Further, minordifferences may be attributed to a temperature shift due to the observeddata being collected at room temperature and calculated data taken froma structure at 120K.

The tosylate salt, specifically the crystalline mono salt, was confirmedand the diffraction pattern is shown in FIG. 14 using CuKα radiation (40kV, 40 mA), Θ-Θ goniometer, V20 divergence and receiving slits, agraphite secondary monochromator, and a scintillation counter. An XRPDdiffractogram of the tosylate salt after 1 week at 40° C./75% RH revealsa change but the sample is still Form 1. Likely, the change is due to amore hydrated form.

VII. BIOLOGICAL ASSAYS

The ability of Compound A and its stereoisomers to bind to and modulatethe function of various NNR subtypes was assessed as described in U.S.Pat. No. 6,953,855 to Mazurov et al, the contents of which are herebyincorporated by reference. Receptor selectivity profiling for Compound A(including 5HT₃ and muscarinic) was conducted by NovaScreen® BiosciencesCorporation.

Electrophysiological measurement of α7 NNR response were taken in twoexpression systems: rat α7 NNR in mammalian GH4C1 cells and human α7 NNRin Xenopus oocytes.

The GH4C1 cells expressing the rat α7 NNR were prepared as described byPlaczek et al., Mol. Pharm. 68(6): 1863-1876 (2005), incorporated byreference. Electrophysiological measurements of agonist activity wereachieved using the Dynaflow rapid perfusion system and patch clamp usingthis GH4C1 cell expression system. Both acetylcholine and nicotineproduced concentration-dependent activation of the α7 mediated current.Agonist EC₅₀ values from literature were comparable to those obtainedusing this method (see Dunlop et al. Biochem Pharmacol in press (2007)and Dynaflow online materials (www.cellectricon.com), each incorporatedby reference with regard to such method).

Whole-cell currents recorded with an Axopatch 700A amplifier werefiltered at 1 kHz and sampled at 5 kHz by a PCI card (NationalInstrument). Compared with previous studies the saline solutions weremodified as indicated to increase the current stability. Cells wererecorded at room temperature in the following extracellular medium: 130mM NaCl, 5 mM KCl, 2 mM CaCl₂, 2 mM MgCl₂, 10 mM HEPES, adjusted to pH7.4 with aqueous NaOH. Borosilicate electrodes (3-5 MΩ) were filled withthe following medium: 130 mM TRIS phosphate, 5 mM NaCl, 2 mM MgCl₂, 10mM HEPES, 10 mM EGTA, adjusted to pH 7.4 with aqueous KOH (see Wu etal., J. Physiol. 576: 103-118 (2006), incorporated by reference withregard to such teaching). Under these conditions, the macro-currentactivity obtained with NNR whole-cell recording lasts up to 60 min whenelicited with a 1000 μM acetylcholine (ACh) concentration.

Cell handling procedures were adopted from Cellectricon applicationnotes for Dynaflow. Briefly, after removal from the incubator, cellswere washed thoroughly three times with recording medium and placed onthe stage of a inverted Zeiss microscope. On average 5 min was necessarybefore the whole-cell recording configuration was established. To avoidmodification of the cell conditions, a single cell was recorded persingle load of cells into Dynaflow silicon chip. No differences in thefraction of responsive cells could be detected among experimentalconditions. More than 95% of the cells responded to ACh, and every cellpresenting a measurable current was taken into account. Cells were heldat −60 mV throughout the experiment. All test article solutions wereprepared daily from stock solutions. Fresh acetylcholine (ACh) stocksolution was made daily in Ringer's solution and diluted. Dose responsecurves were described by single Hill equations using Prism 5.0 software.

Xenopus oocytes expressing human α7 NNR were prepared as described byPapke and Papke, Brit. J. Pharmacol. 137: 49-61 (2002), incorporated byreference. Mature (>9 cm) female Xenopus laevis African toads (Nasco,Ft. Atkinson, Wis.) were used as a source of oocytes. Prior to surgery,the toads were anesthetized by placing the animal in a 1.5 g/L solutionof 3-aminobenzoic acid ethyl ester for 30 min. Oocytes were removed froman incision made in the abdomen.

In order to remove the follicular cell layer, harvested oocytes weretreated with 1.25 mg/mL collagenase from Worthington BiochemicalCorporation (Freehold, N.J.) for 2 hours at room temperature incalcium-free Barth's solution (88 mM NaCl, 1 mM KCl, 15 mM HEPES pH 7.6,0.81 mM MgSO₄, 2.38 mM NaHCO₃, 0.1 mg/mL gentamicin sulfate).Subsequently, stage 5 oocytes were isolated and injected with 50 mL(5-20 ng) each of the human α7 cRNA. Recordings were made 2 to 7 daysafter injection. Fresh acetylcholine (ACh) stock solutions were madedaily in Ringer's solution.

Experiments were conducted using OpusXpress 6000A (Axon Instruments,Union City Calif.). OpusXpress is an integrated system that providesautomated impalement and voltage clamp of up to eight oocytes inparallel. Both the voltage and current electrodes were filled with 3 MKCl. Cells were voltage-clamped at a holding potential of −60 mV. Datawere collected at 50 Hz and filtered at 20 Hz. Cells were bath-perfusedwith Ringer's solution, and agonist solutions were delivered from a96-well plate via disposable tips, which eliminated any possibility ofcross-contamination. Flow rates were set at 2 mL/min. Drug applicationsalternated between ACh controls and experimental agonists. Applicationswere 12 seconds in duration followed by 181 second washout periods.

Responses were calculated as net charge (see Papke and Papke, Brit. J.Pharmacol. 137: 49-61 (2002), as cited above) for α7 receptors. Eachoocyte received an initial control application of ACh, then anexperimental drug application, and then a follow-up control applicationof ACh (300 μM). Responses to experimental drug applications werecalculated relative to the preceding ACh control responses in order tonormalize the data, compensating for the varying levels of channelexpression among the oocytes. Note that 300 μM ACh evoked maximal netcharge responses from α7 receptors so that normalization to the AChcontrols effectively normalized the data to ACh maximum responses. Meansand standard errors (SEM) were calculated from the normalized responsesof at least four oocytes for each experimental concentration. Forconcentration-response relations, data derived from net charge analyseswere plotted using Kaleidagraph 3.0.2 (Abelbeck Software; Reading, Pa.),and curves were generated from the Hill equation.

Behavioral characterization of Compound A was conducted according to thefollowing protocols. The object recognition (OR) task was performed inaccord with the description of Ennaceur and Delacour Behav. Brain Res.100: 85-92 (1988), incorporated by reference. The radial arm maze (RAM)paradigm was performed in accord with the description of Levin et al.,Behav. Pharm. 10: 675-680 (1999), incorporated by reference. Thepre-pulse inhibition (PPI) assay was performed in accord with thedescription of Suemaru et al., Brit. J. Pharmacol. 142(5): 843-850(2004). The reversal of apomorphine-induced locomotor activity (APOLOCO) assay was performed in accord with the description of Roux et al.,Curr. Protocols in Pharmacol. Unit 5.17 (1999).

Summary of In Vitro Biological Activity

Compound A competitively inhibits the binding of radiolabeled MLA to ratbrain hippocampus α7 NNRs with an equilibrium constant (Ki) values of ˜1nM, indicating that it has a very high affinity for the α7 NNR subtype.The stereoisomers of Compound A have the following Ki values at rat α7NNRs: 2R,3S (42 nM) [previously reported as 28 nM]; 2R,3R (1 nM); 2S,3S(25 μM) (see FIG. 1A). As illustrated in FIG. 1A.2, Compound A, the2S,3R enantiomer, demonstrates an activity at the α7 subtype in contrastto its three enantiomeric analogs, which are represented as overlappingpoints with weak activity. Compound A does not bind to α4β2 NNRs withany significant affinity (Ki values>2 μM).

The functional activity of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof (Compound A) and itsstereoisomers was examined using patch clamp electrophysiologicaltechniques with rat α7 NNRs stably expressed in GH4C1 (mammalian) cells.In these experiments, Compound A produced a remarkably differentfunctional profile in comparison to the other individual isomers and tothe racemic mixture of all four isomers. As can be seen in FIGS. 1A and1B, Compound A is much more potent and efficacious at elicitingfunctional response (E_(max)=93% relative to acetylcholine (ACh);EC₅₀=14 nM) than any of the other isomers or the mixture of fourisomers. Indeed, Compound A (the 2S,3R isomer) is the only isomer ofN-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidethat is able to provide potent agonism throughout the concentrationrange of 1-50 nM, with 10 nM being associated with in vivo activity asherein described, as shown in FIG. 1B.

The functional activity of Compound A was also electrophysiologicallyevaluated in Xenopus oocytes transiently expressing human α7 NNRs. Inthis system, Compound A has an EC₅₀ value of 33 nM and an E_(max) of100% of ACh response. There were decreases in subsequent controlresponses to ACh following the application of(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideat concentrations greater than 100 nM (IC₅₀=200 nM). In contrast topreviously described α7 full agonists (see Astles et al., Current DrugTargets CNS Neurological Disorders 1(4): 337-348 (2002), incorporated byreference with regard to such reporting), the separation between EC₅₀and IC₅₀ values for(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideindicates that concentrations which produce the half-maximal functionalresponse of α7 lead to minimal, rather than full, residual inhibition.There was no detectable activation when(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidewas applied to oocytes expressing the human α4β2 sub-type and nosignificant decreases in subsequent control responses to ACh, indicatingthat(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideis neither an agonist nor antagonist at α4β2.

The compounds exhibited little or no agonist activity in functionalmodels bearing muscle-type receptors (α1β1γδ subtype in human TE671/RDclonal cells), or ganglion-type receptors (α3β4 subtype in the Shootersubclone of rat pheochromocytoma PC12 cells and in human SHSY-5Y clonalcells), generating≦10% (human muscle), ≦20% (rat ganglion) and ≦10%(human ganglion) of nicotine's response at these subtypes. These dataindicate selectivity for CNS subtypes over PNS subtypes.

Due to the close sequence and structural homology between α7 and5-hydroxytryptamine (5HT₃) receptors, and cross-reactivity to these 2receptors observed with other nicotinic ligands, the affinity ofCompound A to 5HT₃ receptors was investigated. Compound A (10 μM)displayed 59% inhibition of radioligand binding at the mouse 5HT₃receptor and 25% inhibition at the human receptor. Investigation offunctional activation at the human 5HT₃ receptor suggests minimal to noactivation (i.e., a maximal response of 15% activation was obtained at100 μM).

Muscarinic receptors are another area of concern due to interactionsthat have been observed with other nicotinic ligands. Compound Adisplayed minimal to no interaction when examined in competitive bindinginhibition assays for M1, M2, nonselective central and nonselectiveperipheral muscarinic receptors.

The data show that Compound A is selective for α7 NNR ligands. CompoundA does not bind well at those subtypes of the nicotinic receptor thatare characteristic of the peripheral nervous system or at muscarinic or5HT₃ serotinergic receptors. Thus, Compound A possesses therapeuticpotential in treating central nervous system disorders without producingside effects associated with interaction with the peripheral nervoussystem.

Summary of In Vivo Biological Activity

Compound A,(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof, displays significantefficacy in two behavioral models of cognition. Compound A demonstratedpotent activity in the object recognition paradigm in rats, followingboth i.p. (intraperitoneal, FIG. 3) and p.o. (oral, FIG. 4)administration, and also demonstrated activity across a wide dose rangefollowing oral administration (FIG. 4). Administered intraperitoneallyat the same low doses (0.3 and 1 mg/kg) Compound A tends to reverseMK-801 induced deficits in the OR task (FIG. 5), and administered orallyat 0.3 mg/kg Compound A's cognitive effects last for at least 18 hours(FIG. 6). In the radial arm maze (RAM) (FIG. 7) paradigm examiningworking memory, Compound A significantly increased the number of correctchoices prior to error. These results show potential for(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidein treating cognitive deficits and dysfunctions associated withschizophrenia, including those of working memory.

For a compound to be useful for treating the cognitive dysfunction inschizophrenia, it must not diminish the effects of classical or atypicalantipsychotics against the positive symptoms of schizophrenia. Thus, itis compelling that, in addition to its cognitive enhancing properties,Compound A also displays effectiveness in reversing apomorphine-inducedlocomotor activity (APO LOCO) (FIG. 8) and pre-pulse inhibition (PPI)(FIG. 9) models of positive symptoms of schizophrenia. Thus,(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidewould be expected to provide an additional benefit against the positive,as well as the cognitive, symptoms associated with schizophrenia.

The specific pharmacological responses observed may vary according toand depending on the particular active compound selected or whetherthere are present pharmaceutical carriers, as well as the type offormulation and mode of administration employed, and such expectedvariations or differences in the results are contemplated in accordancewith practice of the present invention.

Although specific embodiments of the present invention are hereinillustrated and described in detail, the invention is not limitedthereto. The above detailed descriptions are provided as exemplary ofthe present invention and should not be construed as constituting anylimitation of the invention. Modifications will be obvious to thoseskilled in the art, and all modifications that do not depart from thespirit of the invention are intended to be included with the scope ofthe appended claims.

1.(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof. 2.(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,in substantially pure form, or a pharmaceutically acceptable saltthereof. 3.(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,substantially free of (2S,3S), (2R,3S), or (2R,3R) isomers, or apharmaceutically acceptable salt thereof.
 4. Stereoisomerically enriched(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,or a pharmaceutically acceptable salt thereof.
 5. The stereoisomericallyenriched(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideof claim 4, wherein the enantiomeric or diastereomeric excess isselected from 90% or greater; 95% or greater; 98% or greater; 99% orgreater; or 99.5% or greater.
 6. An acid salt of(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamide,wherein the acid is selected from hydrochloric acid, sulfuric acid,phosphoric acid, maleic acid, toluenesulfonic acid, galactaric (mucic)acid, D-mandelic acid, D-tartaric acid, methanesulfonic acid, R- andS-10-camphorsulfonic acids, ketoglutaric acid, or hippuric acid.
 7. Theacid salt of claim 6 wherein the stoichiometry of(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideto the acid is 2:1, 1:1, or 1:2.
 8. The acid salt of claim 7 wherein thestoichiometry is 1:1. 9.(2S,3R)-(2-((3-pyridinyl)methyl)-3-amino-1-azabicyclo[2.2.2]octane. 10.A method for treating or preventing a central nervous system disorder,inflammation, pain, or neovascularization comprising administering acompound of claim 1
 11. The method of claim 10, wherein the centralnervous system disorder is characterized by an alteration in normalneurotransmitter release.
 12. The method of claim 10, wherein thecentral nervous system disorder is selected from mild cognitiveimpairment, age-associated memory impairment, pre-senile dementia, earlyonset Alzheimer's disease, senile dementia, dementia of the Alzheimer'stype, Alzheimer's disease, Lewy Body dementia, micro-infarct dementia,AIDS-related dementia, HIV-dementia, multiple cerebral infarcts,Parkinsonism, Parkinson's disease, Pick's disease, progressivesupranuclear palsy, Huntington's chorea, tardive dyskinesia,hyperkinesia, mania, attention deficit disorder, attention deficithyperactivity disorder, anxiety, depression, dyslexia, schizophrenia,cognitive dysfunction in schizophrenia, depression, obsessive-compulsivedisorders, or Tourette's syndrome.
 13. The method of claim 10, whereinthe central nervous system disorder is selected from Alzheimer'sdisease, mania, attention deficit disorder, attention deficithyperactivity disorder, anxiety, dyslexia, schizophrenia, cognitivedysfunction in schizophrenia, depression, obsessive-compulsivedisorders, or Tourette's syndrome.
 14. A method of manufacturing(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof comprising sequentialdynamic resolution and stereoselective reductive amination of(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-one.
 15. A method ofmanufacturing(2S,3R)—N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof comprising(2S,3R)-(2-((3-pyridinyl)methyl)-3-amino-1-azabicyclo[2.2.2]octane. 16.(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidehydrochloride or a hydrate or solvate thereof. 17.(2S,3R)—N-(2-((3-pyridinyl)methyl)-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamidemonohydrochloride or a hydrate or solvate thereof.
 18. A pharmaceuticalcomposition comprising(2S,3R)N-(2-((3-pyridinyl)methyl-1-azabicyclo[2.2.2]oct-3-yl)benzofuran-2-carboxamideor a pharmaceutically acceptable salt thereof and one or morepharmaceutically acceptable diluent, excipient, or carrier.
 19. Thepharmaceutical composition of claim 18 wherein the pharmaceuticallyacceptable salt is the hydrochloride or a hydrate or solvate thereof.20. The pharmaceutical composition of claim 18 wherein thepharmaceutically acceptable salt is the monohydrochloride or a hydrateor solvate thereof.